Touches a lot of code to remove long constants like "1L", so this patch is
large and ugly, but I think it makes all those Clamp() calls look nicer in
the long run.
Most of the game is 64-bit clean, since we can build without assembly code
now. I've marked the things that are obviously still wrong with STUBBED lines.
That being said: a 64-bit build can already run the demos mostly correctly,
so we're actually almost there!
There are a few obvious things that are obviously wrong, to be fixed.
This was a _ton_ of changes, made 15 years ago, so there are probably some
problems to work out still.
Among others: Engine/Base/Stream.* was mostly abandoned and will need to be
re-ported.
Still, this is a pretty good start, and probably holds a world record for
lines of changes or something. :)
