Merge remote-tracking branch 'origin/master'

essentials vanish support and dont let people accept in cancelled trades

Fix stack overflow / save logs

Configure slots, re-open inv if typing an offer when cancelled

Add %LEVELS% to xp display option, translate color codes

Show amount of levels player can receive from accepting xp offers.

Options to disable spectating

Fix bug with enchantment api

Catch the error if worldguard isn't installed

3.68