Added /clearchat Command. Use /clearchat to clear your own Chat. /clearchat player <player> to clear another Players Chat. /clearchat server <server> to clear the Chats on the whole Server.

Needs Permissions:
/clearchat -> cloudchat.command.clearchat
/clearchat player <player> -> cloudchat.command.clearchat.other
/clearchat server <server> -> cloudchat.command.clearchat.server