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

[jsm174]

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]

great work. @zesinger these changes are required because any other operating system except Windows uses case sensitive file systems. And serum files obviously don't use a consistent file extension, so sometimes upper and sometimes lower case.

[zesinger]

Sorry, I prefer libserum to remain pure C code. Could you remove all the "::" (like "std::string" and such) and replace them by pure C (like "char*"), please? "std::chrono::duration_caststd::chrono::milliseconds(std::chrono::system_clock::now().time_since_epoch()).count();" was accepted as this is cross platform and I had nothing to propose as an equivalent.
Thanks

[jsm174]

Sorry, I prefer libserum to remain pure C code. Could you remove all the "::" (like "std::string" and such) and replace them by pure C (like "char*"), please? "std::chrono::duration_caststd::chrono::milliseconds(std::chrono::system_clock::now().time_since_epoch()).count();" was accepted as this is cross platform and I had nothing to propose as an equivalent. Thanks

Ok. Understood. I figured the door was open for C++, as the file is named serum-decode.cpp and the use std::chrono.

I tried to make the code as simple as possible, but I'll rework the code to use C. I will somehow have to get dirent.h in for Windows builds.