Jb/add package manager

[bennedich]

Package loader reads lua defined package files and loads resources using standalone bitmap loader and shader loader. OpenGL specific texture manager and shader manager manages gpu resource usage.

[seriema]

I went through all the commits. There are a few issues. I'd like us to maintain working commits at all times. Partly for us to be able to jump back and forth in history without problems, but also to uphold some level of craftsmanship.

See the list below (ticked checkbox means the build passes). I was able to create a branch from your PR where I fix those issues as separate commits. That should help you fix these issues. You can move/squash some of your own commits where you already fix a few issues, but most of the issues are best fixed by updating test.cpp to load, unload, and delete resources similar to main.cpp.

• [x] Basic project architecture. 1d1a597
• [ ] Bitmap resource loader. Basic texture manager. 3c19576 test.sh: libc++abi.dylib: terminating with uncaught exception of type std::out_of_range: unordered_map::at: key not found
• [ ] Shader resource loader. 551b4e8 build.sh: Cannot find source file: src/shader.h
• [ ] Forgot a file. 906a7a2 test.sh: libc++abi.dylib: terminating with uncaught exception of type std::out_of_range: unordered_map::at: key not found
• [ ] Include cstring for std::strcpy. Explicitly delete vert and frag sour… 001b308 test.sh: libc++abi.dylib: terminating with uncaught exception of type std::out_of_range: unordered_map::at: key not found
• [ ] Basic gui renderer that draws rects. 36ff5ce ./scripts/test.sh: line 7: 34203 Segmentation fault: 11 ./a_retro_test
• [ ] Render clockwise triangle strips. efeff36 ./scripts/test.sh: line 7: 34486 Segmentation fault: 11 ./a_retro_test
• [x] Add resources to test. Delete gui renderer on shutdown. cf118e6
• [ ] Package loader reading lua defined packages. f743d7a ./scripts/test.sh: line 7: 35045 Segmentation fault: 11 ./a_retro_test
• [x] Make standard container members non-const. 1a74750
• [x] Some more standard container members turned into non-const. 284d446
• [x] Replaced usage of std::unordered_map::operator with std::unord… 0cea4c3
• [x] Crashfix indexing outside of array when removing resources. 7444729 Not needed? Does it actually fix a real issue?