@renamechannel

Renames a channel. This is convenient for changing a channel name without
having to destroy and recreate it.

Usage:

@renamechannel foo = bar
@renamechannel unclassified/foo = bar (renames to unclassified/bar)
@renamechannel unclassified/foo = games/ (switches foo to the games category)
@renamechannel unclassified/foo = games/foo (ditto)