Bug introduced with e97d3288. This doesn't work with MinGW, since
the struct members might not be aligned to the native pointer
size (in this case idSampleDecoderLocal was aligned to a 8 byte
boundary on win32).
Just switch the two members to avoid ugly code.
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.
