Abstract zip (de)compression, add implode/reduce/shrink/deflate64 support

[AliceLR]

• Initial zip compression/decompression stream implementation.
• Compare local and central directory flags values and ignore unused flags.
• enum zip_error and error strings cleanup.
• Shrink (1) decompressor
• Reduce (2-5) decompressor
• Implode (6) decompressor
• Deflate64 (9) decompressor (maybe...)
• Only enable extra decompressors for 1) builds with utils and 2) HTML5.
• Prevent world/etc loaders from recognizing files using formats other than store and deflate.
• Check if the special case LE code in bitstream is worth uncommenting.
• Support for actually streaming inflate/deflate + switch counter and string to stream deflate instead of store. 2 much work right now :(
• Emscripten
• Testing
• MOAR TESTING
• Cleanup as much as i'm willing to stomach, the rest can wait until 2.93

See this DigitalMZX post for a list of games archived with these compression methods.