update gettext configuration to not include any generated files in git before we had a somewhat mixed setup, which seems to create problems when a different gettext version was installed on the users machine compared to the version used to generate the files in git. This should solve the problem. The user will now have to generate these files using autopoint, which we call from autogen.sh.
added/fixed i18n support via gettext to xboard this was already added a long time ago, but now it's added again to autoconf. Also fixed some compile errors that showed up.