Add Splat for binary splitting

[TheOnlyZac]

This PR adds Splat as a submodule for binary splitting. It also cleans up the project documentation files and moves the header files from the src directory to a separate include dir.

[Yotona]

Splat was recently updated to be a pip library instead (v21.0), no longer requiring to be added directly into a repository. Simple installation instructions have been updated in its main readme. We are still working on improving implementation for PS2 titles, thanks for your interest!

[TheOnlyZac]

Thank you to everyone who helped with this, particularly @Yotona, @Mc-muffin, and @ethteck!