Copy user list on _destroy_channel to prevent runtime error.
Fix channel modes in ISUPPORT not being correctly recorded.
Don't add prefixes to valid channel modes, but their modes.
Replace hardcoded mode behaviours.
Make a deep copy of behaviour dictionaries to prevent shared instances.
Make deep copy of limit dictionaries too.
Fix constant name typo in LIST_LIMITS_GROUPS.
Merge branch 'master' into async
Merge branch 'master' into async