Team-comtress-2: 64-bit compatibility

[melvyn2]

Is your feature request related to a problem? Please describe.
Slightly; Memory usage runs dangerously close to the 32-bit limit, especially on macOS due to texture memory allocation issues.

Describe the solution you'd like
Overhaul 32-bit specific code so that it does not rely on a specific memory size, and add 64-bit code with #ifdefs in areas that are not possible to generalize.

Describe alternatives you've considered
Fix the memory fragmentation issues on the platforms on which this is an issue.

Additional context
Very High texture quality is disabled on macOS for this reason.
ValveSoftware/Source-1-Games#2238 contains a lot of pertinent information.
Additionally, both CS:GO and Garry's Mod have been ported to 64-bits.

[micwoj92]

@melvyn2 with Apple moving to arm, amd64 based macos machines will be obsolete.

[melvyn2]

Intel macs will still be supported for at least 5 years, probably 7, so they will still not be obsolete for a while.

[micwoj92]

Valve time.

[melvyn2]

I just realized #67 exists; I'll move the extra info there and close this issue.