gnu: Add texlive-latex-float.

* gnu/packages/tex.scm (texlive-latex-float): New variable.

gnu: Add texlive-latex-fancyvrb.

* gnu/packages/tex.scm (texlive-latex-fancyvrb): New variable.

gnu: Add texlive-latex-fancyhdr.

* gnu/packages/tex.scm (texlive-latex-fancyhdr): New variable.

gnu: Add texlive-latex-fancybox.

* gnu/packages/tex.scm (texlive-latex-fancybox): New variable.

gnu: Add texlive-latex-colortbl.

* gnu/packages/tex.scm (texlive-latex-colortbl): New variable.

gnu: Add texlive-latex-changebar.

* gnu/packages/tex.scm (texlive-latex-changebar): New variable.

gnu: Add texlive-latex-appendix.

* gnu/packages/tex.scm (texlive-latex-appendix): New variable.

gnu: Add texlive-latex-anysize.

* gnu/packages/tex.scm (texlive-latex-anysize): New variable.

gnu: Add texlive-latex-amsfonts.

* gnu/packages/tex.scm (texlive-latex-amsfonts): New variable.

gnu: Add texlive-fonts-amsfonts.

* gnu/packages/tex.scm (texlive-fonts-amsfonts): New variable.

gnu: texlive-generic-ifxetex: Fix description.

* gnu/packages/tex.scm (texlive-generic-ifxetex)[description]: Fix typo.

gnu: texlive-latex-oberdiek: Build ifpdf package.

* gnu/packages/tex.scm (texlive-latex-oberdiek)[arguments]: Only build the
"oberdiek.ins" package (which includes all other packages); patch file to
build "ifpdf.dtx" instead of "ifpdf.ins".

gnu: texlive-latex-base: Fix xetex and xelatex formats.

* gnu/packages/tex.scm (texlive-latex-base)[arguments]: Build xetex and
xelatex formats with matching interpreters.

build-system: texlive: Build union in configure phase.

This allows us to use texmf.cnf instead of having to set all required
environment variables manually.

* guix/build/texlive-build-system.scm (configure): New procedure.
(build): Simplify.
(%standard-phases): Add configure phase.
* guix/build-system/texlive.scm (texlive-build): Include (guix build union) in
modules.
(%texlive-build-system-modules): Likewise.

build-system: texlive: Only build packages in the current directory.

* guix/build/texlive-build-system.scm (build): Use scandir instead of
find-files.

gnu: deeptools: Update to 2.5.1.

* gnu/packages/bioinformatics.scm (deeptools): Update to 2.5.1.
[arguments]: Remove.
[native-inputs]: Use "python-" instead of "python2-" variants.
[inputs]: Likewise; add python-py2bit.

gnu: Add python-py2bit.

* gnu/packages/bioinformatics.scm (python-py2bit): New variable.

gnu: Add java-jgit-4.2.

* gnu/packages/version-control.scm (java-jgit-4.2): New variable.

gnu: Add java-jgit.

* gnu/packages/version-control.scm (java-jgit): New variable.

gnu: Add java-slf4j-api.

* gnu/packages/java.scm (java-slf4j-api): New variable.