This is supposed to be come the place where all pure play code should be placed, but for that all CVARs and CCMDs and other things that do not directly handle play data should be taken out to make code reviewing easier. These now get collected in two separate files, g_cvars.cpp and g_dumpinfo.cpp respectively.
The sole ZScript property in here has also been moved - to thingdef_properties.cpp.
This made reviewing the code for accessing the global state hard, because the doomdef.h contains mainly constants, this particular item was the only thing in there that represents actual engine state.
The Map loader may not access any global state at all - everything it can touch must be exchangable.
Furthermore, if we want to sandbox each level, there may be no direct access to any kind of global state whatsoever from the play code.
It used the current console player's camera, not the actual camera being used for rendering. Although this is the same most of the time, let's better do it right.
This also removes a few leftover references to the player array elsewhwere in the hardware renderer
All these required access to the sector's Level reference.
The remaining references to the global 'level' variable are all in deprecated functions which is ok.
LevelLocals on the left side of.a function call will now always be remapped to 'Level', which will either remap to the same-named instance variable or the global deprecated one.
In a few degenerate cases where there is a conflicting local variable named 'level' it may error out but that is unavoidable here but this is very unlikely.
- moved parts of the render setup out of the separate render functions.
Things like particle and polyobject linking were duplicated several times for rendering different things in different renderers.
These things only need to be set up once before the renderer is started so it makes a lot more sense to consolidate them into one place outside the actual rendering code.
This had two different flags that were checked totally inconsistently, and one was not even saved.
Moved everything into a few subfunctions so that these checks do not have to be scattered all over the code.
