Feature request: better randomness

[jbodner09]

Currently, random numbers are generated in code_800FD970.c in a very fast but potentially predictable way. Since we have access to C++'s library, we should make use of it (behind a cvar) for much more random randomness. It should be easy to add a Mersenne Twister 19937 generator in OTRGlobals that can be called in the existing random number functions when necessary.

[Kenix3]

#404