Fix various issues for 1.30.x

[bhughes339]

• Prevent sporadic "invalid continuation byte" error
• Add support for 12 new slot colors
• Fix issue in Player.from_raw() which threw off byte seeking for the rest of the file
  • Usually custom_or_ladder should be 1 or 8, but it seems to often be 2 for newer replays
• SlotRecord.from_raw(): Drop 2 high-order bits in the "race" byte as per w3g_format.txt - 4.12 notes
• Add new result to LeftGame. Not sure what it is, but it seems to be another version of 'left game'
• Add default value for Select Modes
• File.player_race(): Try to guess actual race for Random players
• Add another "win condition" by finding the last Player who left the game

Resolves: #5 #6

[scopatz]

Awesome work here! Thanks! I'll get a release out today.