Big code cleanup

[jmickle66666666]

My code is very messy! It's not fun sometimes!

GameSetup.cs is huge and not organised at all, much can be split out into separate source files
DoomGraphic.cs's static functions to build graphics are kind of a bad idea? I can go about this in a better way
I want a WadUtil file to have static functions for quick things like building the palette and other little things. Macros basically
Mapbuilder is messy, especially the line building section
SectorTriangulator could be nicer, but it's also unfinished