[KBSwitch] Link to xkbfile.
[KBSwitch] Load & store rules/layouts.
[KBSwitch] Fixed a typo.
[KBSwitch] KBCtl::GetCurrentGroup().
[KBSwitch] Added QuarkProxy.
[KBSwitch] Added layout quark.
[KBSwitch] Added FlagIconProvider.
[KBSwitch] Show keyboard layout flag.