Some entities wrote the handle from gameRenderWorld->AddLightDef()
into savegames and reused it after restoring it.
That's a bad idea, because at that point the handle most likely belongs
to something else (likely some idLight). The most visible issue this
can create is that the flashlight may not work correctly after loading
a savegame with flashlight on, when it happens to alias a light that's
updated each frame to (mostly) being off..
The correct way to handle this (THAT FOR SOME REASON WAS ALREADY
IMPLEMENTED IN D3XP BUT NOT THE BASE GAME - WHY?!) is to get a fresh
handle with AddLightDef() when restoring a savegame - unless the handle
was -1, which means that the light didn't exist when saving.
fixes#495
Don't include the lazy precompiled.h everywhere, only what's
required for the compilation unit.
platform.h needs to be included instead to provide all essential
defines and types.
All includes use the relative path to the neo or the game
specific root.
Move all idlib related includes from idlib/Lib.h to precompiled.h.
precompiled.h still exists for the MFC stuff in tools/.
Add some missing header guards.
