Add teams and donations

[TomfoolerousGitHub]

• Added team functionality via a new Team class, which is stored as an attribute of each player. Number of teams is customizable when initializing the player manager.
• Donations are handled by a DonationExecutor class, based off the corresponding class for attacks. Its fairly barebones, but can be edited easily if we want to do something with donations.
  • Donations are treated the same as an attack, so clicking on a teammate executes a donation instead.
• This depends on a few parts marked for removal/refactoring, but it should be moved easily enough.

[theotherhades]

Also, networking should probably be implemented before gameplay features such as this.

[platz1de]

As of fdf8778 the neccessary abstraction is now added, sorry for the long delay Donations (as discussed in the discord) will probably just be automatically adding troops to neighbor players, without having to interact with the player directly