doc: Add subsections to 'Invoking guix build'.

* doc/guix.texi (Invoking guix build): Add example.  Shuffle options in
the new subsections below.
(Common Build Options, Additional Build Options): New nodes.
(Invoking guix archive): Refer to "Common Build Options".
(Invoking guix environment): Likewise.
(Invoking guix system): Likewise.

fixlet

guix build: Transformations operate on single objects.

* guix/scripts/build.scm (transform-package-source): Return a procedure
that expects a single object rather than a list of packages.
(options->transformation): Rewrite to precompute the list of applicable
transformations and to return a procedure that expects a single object
rather than a list of objects.
(options->derivations): Adjust accordingly.
* tests/scripts-build.scm: New file.
* Makefile.am (SCM_TESTS): Add it.

install: Make it clear that we refer to the root by label.

* gnu/system/install.scm (installation-os): Use (title 'label) for the
root file system.

build: Use the right section and source for man pages.

* doc.am (HELP2MANFLAGS): New variable.
(gen_man): Use it.

gnu: Add pinball.

* gnu/packages/games.scm (pinball): New variable.
* gnu/packages/patches/pinball-const-fix.patch,
  gnu/packages/patches/pinball-cstddef.patch,
  gnu/packages/patches/pinball-missing-separators.patch,
  gnu/packages/patches/pinball-src-deps.patch,
  gnu/packages/patches/pinball-system-ltdl.patch: New patches.
* gnu-system.am (dist_patch_DATA): Add them.

gnu: python-apsw: Update to 3.9.2-r1.

* gnu/packages/python.scm (python-apsw): Update to 3.9.2-r1.
[source]: Change to pypi uri syntax.

gnu: wayland: Build documentation.

* gnu/packages/freedesktop.scm (wayland)[native-inputs]: Add graphviz.

gnu: python-pillow: Update to 3.1.0.

* gnu/packages/python.scm (python-pillow): Update to 3.1.0.
[source]: Change to pypi uri syntax.

gnu: Add aseprite.

* gnu/packages/game-development.scm (aseprite): New variable.

gnu: Add allegro-4.

* gnu/packages/game-development.scm (allegro-4): New variable.

license: Add giftware.

* guix/licenses.scm (giftware): New variable.

gnu: obs: Update to 0.13.0.

* gnu/packages/video.scm (obs): Upgrade to 0.13.0.

gnu: perl-tk: Update to 804.033.

* gnu/packages/tcl.scm (perl-tk): Update to 804.033.
[source]: Remove patch.
* gnu/packages/patches/perl-tk-x11-discover.patch: Remove file.
* gnu-system.am (dist_patch_DATA): Remove patch.

gnu: weechat: Update to 1.4.

* gnu/packages/weechat.scm (weechat): Update to 1.4.

gnu: pumpa: Update to 0.9.2.

* gnu/packages/pumpio.scm (pumpa): Update to 0.9.2.
[source]: Add 'file-name' field.

build: Generate man pages after compiling Guile objects.

This reduces compilation time since scripts are not compiled twice.
When building with 'make -j4' from a clean repository on an Intel
i5-2540M, compilation time gets from:

real	4m48.708s
user	17m29.892s
sys	0m9.596s

down to:

real	2m23.399s
user	6m48.604s
sys	0m6.420s

* doc.am (subcommand-manual-target): Delete function.
(SUBCOMMANDS): Delete variable.
(sub_command_mans, gen_man): New variables.
(dist_man1_MANS): Add $(sub_commands_mans).
(doc/guix-%.1): New target for sub-commands man pages.  It ensures that
man pages are built only after compiling Guile objects.
(doc/guix-daemon.1): Use $(gen_man).  Build only if BUILD_DAEMON.
(doc/guix.1): Use $(gen_man).  Add $(sub_command_mans) prerequisite.

Co-authored-by: Mathieu Lirzin <mthl@gnu.org>

Rename 'dmd' to 'shepherd' in comments and strings.

* build-aux/hydra/demo-os.scm (operating-system)[issue]: Point to
  shepherd instead of dmd.
* ROADMAP: Likewise.
* gnu/build/install.scm (directives): Adjust comment.

guix system: Rename 'dmd-graph' to 'shepherd-graph'.

* doc/images/dmd-graph.dot: Rename to...
* doc/images/shepherd-graph.dot: ... this.
* doc.am (DOT_FILES): Adjust accordingly.
* guix/scripts/system.scm (dmd-service-node-label)
  (dmd-service-node-type, export-dmd-graph): Rename to...
  (shepherd-service-node-label, shepherd-service-node-type)
  (export-shepherd-graph): ... this.
  (show-help, process-action, process-command): Rename 'dmd-graph' to
  'shepherd-graph'.
* emacs/guix-command.el (guix-command-additional-execute-arguments)
  (guix-command-special-executors): Likewise.
* doc/guix.texi: Likewise.
* doc/emacs.texi (Emacs Popup Interface): Likewise.

services: Rename 'dmd' services to 'shepherd'.

* gnu/services/shepherd.scm (dmd-root-service-type, %dmd-root-service)
  (dmd-service-type, <dmd-service>, dmd-service, dmd-service?)
  (make-dmd-service, dmd-service-documentation, dmd-service-provision)
  (dmd-service-requirement, dmd-service-respawn, dmd-service-start)
  (dmd-service-stop, dmd-service-auto-start?, dmd-service-modules)
  (dmd-service-imported-modules, dmd-service-file-name, dmd-service-file)
  (dmd-service-back-edges): Rename to...
  (shepherd-root-service-type, %shepherd-root-service, shepherd-service-type)
  (<shepherd-service>, shepherd-service, shepherd-service?)
  (make-shepherd-service, shepherd-service-documentation)
  (shepherd-service-provision, shepherd-service-requirement)
  (shepherd-service-respawn, shepherd-service-start)
  (shepherd-service-stop, shepherd-service-auto-start?)
  (shepherd-service-modules, shepherd-service-imported-modules)
  (shepherd-service-file-name, shepherd-service-file)
  (shepherd-service-back-edges): ...this
* gnu/services.scm: Adjust comments.
* gnu/services/avahi.scm (avahi-dmd-service): Rename to...
  (avahi-shepherd-service): ... this.
* gnu/services/base.scm (%root-file-system-dmd-service)
  (file-system->dmd-service-name, mapped-device->dmd-service-name)
  (dependency->dmd-service-name, file-system-dmd-service)
  (mingetty-dmd-service, nscd-dmd-service, guix-dmd-service)
  (guix-publish-dmd-service, udev-dmd-service, gpm-dmd-service): Rename to...
  (%root-file-system-shepherd-service)
  (file-system->shepherd-service-name, mapped-device->shepherd-service-name)
  (dependency->shepherd-service-name, file-system-shepherd-service)
  (mingetty-shepherd-service, nscd-shepherd-service, guix-shepherd-service)
  (guix-publish-shepherd-service, udev-shepherd-service)
  (gpm-shepherd-service): ... this.
* gnu/services/databases.scm (postgresql-dmd-service): Rename to...
  (postgresql-shepherd-service): ... this.
* gnu/services/desktop.scm (upower-dmd-service, elogind-dmd-service):
  Rename to...
  (upower-shepherd-service, elogind-shepherd-service): ... this.
* gnu/services/dbus.scm (dbus-dmd-service): Rename to...
  (dbus-shepherd-service): ... this.
* gnu/services/lirc.scm (lirc-dmd-service): Rename to...
  (lirc-shepherd-service): ... this.
* gnu/services/mail.scm (dovecot-dmd-service): Rename to...
  (dovecot-shepherd-service): ... this.
* gnu/services/networking.scm (ntp-dmd-service, tor-dmd-service)
  (bitlbee-dmd-service, wicd-dmd-service, network-manager-dmd-service): Rename to...
  (dbus-shepherd-service): ... this.
* gnu/services/ssh.scm (lsh-dmd-service): Rename to...
  (lsh-shepherd-service): ... this.
* gnu/services/web.scm (nginx-dmd-service): Rename to...
  (nginx-shepherd-service): ... this.
* gnu/services/xorg.scm (slim-dmd-service): Rename to...
  (slim-shepherd-service): ... this.
* gnu/system.scm (essential-services): Use '%shepherd-root-service'.
* gnu/system/install.scm (cow-store-service-type): Adjust accordingly.
* guix/scripts/system.scm (dmd-service-node-label, dmd-service-node-type)
  (export-dmd-graph): Likewise.
* tests/guix-system.sh: Likewise.
* tests/services.scm ("dmd-service-back-edges"): Rename to...
  ("shepherd-service-back-edges"): Adjust accordingly.
* doc/guix.texi: Likewise.
* doc/images/service-graph.dot: Use 'shepherd' service name.

services: xorg: Use 'shepherd' instead of 'dmd'.

* gnu/services/xorg.scm (slim-configuration-dmd): Rename to...
  (slim-configuration-shepherd): ... this.
  (slim-shepherd-service): Adjust accordingly.
  (slim-service): Take 'shepherd' keyword argument.