Add function for creating groups (similar to the100)

[tuzonghua]

• .creategroup, .disbandgroup, .joingroup, .leavegroup, .listgroups
• Variables to pass through can be can be custom text, don't know how should work, only necessary since everyone should be required to join in the channel.
• Reminders sent to .joingroup users an hour before event starts
• Should happen in PM only
• When .creategroup is used, LittleLight can announce a new group with a random ID generated. If hasn't been filled within an hour remaining, another announcement can be made.