misc: ios simulator builds, case-insensitive files, TMPDIR env var

[jsm174]

This PR supersedes #54 with your requested C++ to C conversion.

• It continues to use the custom strcpy_s and strcat_s functions.
• It removes max and min functions as these are already built into C.
• It fixes some compiler warnings in a IS_DEBUG_READ debug message.

I still need to test Windows side and make sure everything works.

1. This PR adds support for iOS simulator builds.

2. It also updated the loading mechanism to first look for a cROM file, and if not found then look for a cRZ file.

It also adds support for case insensitive filenames on linux and iOS. (ZEDMDOS too)

For example if you wanted a cROM file on linux, and you extract a cRZ on Mac, sometimes I've seen them extract as cRom. Transferring the file over, it would never find it.

3. Last, on ZEDMDOS, since it is BOOT is a write only partition, it adds support for TMPDIR environment var (just like on iOS). So if any platform has a TMPDIR environment var, the file will get decompressed there.

[mkalkbrenner]

After a conversation with @zesinger we agreed to merge #54 instead as it is less code and doesn't introduce another dependency to a third party lib.