name a bunch of globals, functions, move some stuff, general fixes

[freshollie]

• Name some BG Sprite globals
• Create some macros for setting up the BG Sprite globals
• Name gMultiplayerRanks
• Name gOamMallocBuffer
• Name gBgOffsetsHBlank globals
• Name gSpriteOffset
• Name ProcessOamBuffers function
• Move gRefCollision to collision.c
• Name Player_HandleMultiplayerFinish and refactor
• Name gWorldSpeed
• Name gSpikesUnknownTimer