Update todo
Rewrite tests and rework testing framework for ordered tests and critical tests
Fix binding test files and update test loader
Improve Coeus error bubbling

- Add Coeus:CreateError and Coeus:IsError
- Coeus:Error now returns a Coeus error object
Fix bindings that have stopped working
Add ToString methods to vector types
Implement debug and release constructors

Here, I've done a sample implementation for Matrix4. Also added is Matrix4.Add. This is a breaking change, as Matrix4's constructor now takes varargs instead of a table.