Feature Request: Merge parties

[JustusJG]

I'd love a way to merge two parties.

Example:
Tim is leader of party "MickyFans"
Bob is leader of party "MiniFans"

Tim types command /party absorb MiniFans
Bob receives a message, they can type /party accept or /party deny to accept or deny. (duh)
If they accept,
All members of party MiniFans switch to party MickyFans.
All ranks stay the same. Maybe add a parameter /party absorb MiniFans --erase-ranks to change all old MiniFans members to the lowest rank.
XP of party MiniFans gets added to party MickyFans (maybe with multiplier from config).
Add kill counter of MiniFans to MickyFans.
At last, MiniFans gets deleted.