Merge branch 'master' into core-updates Conflicts: Makefile.am guix/scripts/gc.scm guix/scripts/package.scm guix/ui.scm tests/guix-package.sh
gnu: screen: Use GNU mirror. * gnu/packages/screen.scm (screen): Use GNU mirror.
gnu: screen: correct license to gpl2+ * gnu/packages/screen.scm (screen): correct license field
Add GNU Screen. * gnu/packages/screen.scm: New file. * Makefile.am (MODULES): Add it.