Modifiy commands

Remove boss spawning commands, remove deprecation commands, and merge
hardmode commands.
Add command help text

Also remove /debugreg, as it is now pointless.
Refactor some commands...
Update /invade, make /help <command> not work if no access
Modify more commands

Combined /killprojectile and /clearitems
Removed whisper prefix from whisper messages (color should be more than
sufficient)
Removed /star
Added /butcher [mob type]
Removed deprecated command methods
Added /clear npc (/butcher without item drops)
Merge remote-tracking branch 'nyx/general-devel' into general-devel
If /help second argument starts with /, remove it
Merge pull request #620 from MarioE/general-devel

Commands