This commit overhauls the global.dm file, global_lists.dm file, and
defines.dm file into a tree system based on -tg-.
All defines have been split and distributed in code/__DEFINES/
Everything from global.dm and global_lists.dm has been split and
distributed in code/_globalvars
The _compile_options.dm file contains anything that absolutely, 100%, must
be initialized before world.dm.
Name definitions have been moved to code/_globalvars/lists/names.dm.
Other things to note
- All instances of something.z == 2/1/3/5 have been replaced with easily
configurable defines, labeled ZLEVEL_. The map include file can
override these by defining custom ones in it's file, as it is at the
top of the tree.
