Merged base and d3xp together.

[eezstreet]

After this commit, all of the DOOM 3 base code and Resurrection of Evil SDK code exist as one unified codebase, producing two DLLs but sharing 90% of the same code. Anything that is different between them (should) be #ifdef'd out.

The primary motivation for doing this is to eliminate code reuse. I want to develop a mod for both Resurrection of Evil and the base game, but I don't want to make my changes twice. Thus, having a unified codebase like this makes a lot of sense.

[eezstreet]

Particle effects are currently not moving. Will need to fix that before this gets merged in.

[eezstreet]

This should be ready to merge whenever someone has the chance to review it.

[FriskTheFallenHuman]

I've checked the code myself but there's one weird thing i have notice with stock and merged codebase:

This is Mars City 2 map loaded throught console:

And this is the same map on stock pre merge codebase:

It seems like in vanilla the game its supposed to give you the shotgun but you never get the shotgun at all

other than that it seems solid

[FriskTheFallenHuman]

Enpro Plant has the same issue has Mars City 2

Merge Code:

Stock:

[FriskTheFallenHuman]

Seems like something is off with the player inventory / weapons pickup after the merge