Port away from intltool to plain gettext
intltool isn't maintained and gettext can now handle arbitrary XML files.
Drop intltool from autogen.sh and configure.ac.
Add po/LINGUAS file, replacing ALL_LINGUAS in configure.ac.
Unlike intltool, gettext doesn't need special markup in XML files, so rename base.xml.in to base.xml and replace <_description> with .
Update rules/Makefile.am to remove .xml.in rules and intltool references.
Add rules/xkb.its to tell gettext what elements contain translatable strings, and pass it to gettext in po/Makevars.
Finally, update po files.