feat: add option to limit memory to 32Mb

[jsmolina]

Fixes #195

For a 256MB system, fdoom.cfg gets erased on fastdoom startup, and thus no sound is available.

[viti95]

Interesting, maybe we are still allocating to much memory and there isn't memory free for internal C functions. Maybe we can add a command line parameter to limit RAM to fit user needs.

[jsmolina]

Added as optional param.
32MB should be for everyone

said someone randomly on the Internet after the 90s 😂

[jsmolina]

WDYT? @viti95

[viti95]

Sorry I was busy finishing new rendering options. After thinking a bit on it, I think three changes have to be made in order to fix all the new crashes:

• Revert default free memory to what it was before, this has been proven to cause lot's of issues
• Allow user set how much memory can be used for zone memory, for example: "-limitram 32768"
• Allow user override the amount of free memory, for example: "-freeram 4096"

[viti95]

Much better, thanks for adding this feature!