remove \noqueue hint in 'already casting a spell' combat message

With disabled spellqueue the combat message when already casting a spell shows:
"You are already casting a spell, to enable spell queueing use '\noqueue'!"

Please change this to only:
"You are already casting a spell!"

Reasons for changing this:
- spellqueue is enabled by default, so if you disable it you already know the command and dont need to have it shown all the time
- live-like
- less cluttered combat chat