Server Gametype Preference

• A "canon" adaptation of the community-created server option lessbattlevotes.
• If set to "None", voting behaves as before.
• If set to "Race" or "Battle". that gametype is considered the preference.
  • The voting screen is always operated from the perspective of the preferred gametype.
  • If you're in an un-preferred gametype, the third vote option will always allow you to continue the gametype.
  • If the preferred gametype is Race and you've just exited a Battle map, Encore may now appear on the second vote option.
• A number of bugs with voting have been corrected.
  • If kartencore is on, the third vote option will now correctly have Encore applied.
  • If a custom EXE or malformed packet sends an Encore flag alongside a Battle gametype ID, actively strip it.
    • Just to note, clients do not enter Battle Encore with or without this change - this just prevents a promise the rest of the game couldn't fulfill.

ALSO:

• Make a server report its preferred gametype on the MS listing, not its current one.
  • The intent is to stop servers from needing to dedicate their limited name/MOTD space to things like advertising lessbattlevotes, and to avoid "punishing" a server in visibility for allowing temporary gametype switches. However, this is possibly a controversial change, so I'm doing it in its own commit in case there's a clear consensus to revert.