Commands entered using ':' run as a Weechat command after checked against list

When a command is entered using ':', after testing the command against the command list, it is passed through as a command to Weechat. Allows ':' to be the interface for all Weechat commands. If a command is unknown to weechat it will still print 'unknown command' in the main buffer.  Example: ':join #freenode' runs as '/join freenode'

I personally found this to really extend vimode in my own work - though I don't know what route you see this project going long term.