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.
Alot of stack and event variables are pointers. Align the size of
all script and event variable types to sizeof(intptr_t) so that
the CPU needs only one fetch insn on 64bit archs.
Tested on x86 and x86_64 and found no different script behaviours
compared to the binary from id.
Savegames on x86_64 do work, but are not compatible to x86 and vice
versa (among other issues, the stack is written to file as-is).
x86 builds can still load savegames from the official binary and
vice versa.
