Merge pull request #2 from lyokha/master

XKb Switch API for using in vim libcall()
Parser refactoring, new -x option, new --test option
README: add debugging notes
Version bump
README: add VIM section
vim: add vim rules file
Fix formatting
Digits are allowed in group names
Version bump
xkb-group.sh: add xkb-group.sh

xkb-group.sh is cabable of switching between primary (say, 'us') and other
recently used layout.
Fix formatting, fix non-bug error message
README.md: add xkb-group section
global XKeyboard variable my throw

global XKeyboard variable xkb will throw uncatchable exception if X is
not available. This will make vim SIGSEGV: see this issue:
http://github.com/lyokha/vim-xkbswitch/issues/5. In this commit a
wrapper class was introduced that will catch exceptions from XKeyboard()