In idDeclManagerLocal::CreateNewDecl() decl->self->DefaultDefinition();
crashed because self was uninitialized.
Now it gets set to NULL in the constructor and initialized to something
sensible in decl->AllocateSelf();
this is part of #378
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.
