XM module file parser/Symphonia format extension

This crate is still under heavy development, for now only parsing of the patterns and of the header is implemented

This crate's goal is to parse and implement Symphonia's either Decoder or FormatReader traits (or both). It also doesn't depend on any libraries outside Rust.

To try out the parser, try messing around with the only test in tests.rs file. In the future there'll be more actual unit tests.

The following features are implemented:

• Parsing of header
• Parsing of pattern data
• Parsing of instrument data
• Parsing of sample data
• Unit tests
• Demuxing samples
• Generating stream