cleanup - removed `tests/`
move to `control/`
install XML files as documentation
updated README, switched to Markdown
added `*.glade` symlinks

(workaround for `xgettext` to extract the translatable strings)
add the basic package structure
Merge pull request #1 from yast/separate_package

BTW originally in `yast2-installation` the links were created by `Makefile` but that means you need to run 'make -f Makefiles.cvs && make`, with symlinks in Git you can create POT files directly from Git checkout.