Removed build-scripts.

PKGBUILD has been moved to a separate repository.
Added link to [haavard] repository.
Added group chat join/part/name change messages.
Fixed name of peer leaving group chat.
Fixed link in readme.
Added some safeguards against crashes.
Updated group invite callback function signature.
Added error messages  when group chat invites fail.
Prevent crash when twc_chat_new returns NULL.
Implemented /group create.
Create group chat buffer if it's missing in namelist callback.
Use group chat title instead of "Group Chat #" if possible.
Prevent crashes in twc_chat_refresh.
Implemented /topic.
Added group chat title callback.
Formatting.