[Code] 64-bit port

[alt_turo]

Description:
Current code is not 64-bit clean. Pointers are wantonly cast into integers and back. Things like file loading use fread into structs. Some places in the OpenGL renderer use hard-coded offsets into vertex buffers. D3D renderer might do so too.
Building with 64-bit Linux is partially successful. The resulting binary does not work.
Building with 64-bit Mingw is partially succcessful. I don't have the necessary libraries so linking has never been attempted.
Building with 64-bit MSVC has never been attempted.
Building with 64-bit Mac OS X has never been attempted.

Why: On 64-bit OSes there are sometimes compatibility problems with 32-bit binaries

Difficulty: Hard

Timeline: This is going to take a while

Special skills:
Access to both 32 and 64 bit platforms. Lots of patience for dealing with hard bugs.