Refactoring fusion, better test driven development.
Better tests.
Better tests, preliminary do_fusion.
Implemented _is_fusable.
Adding is_fusable tests.
Preliminary _fuse definition.
Rework fuse blocks logic to create lists of fusables first.
Working array-array fusion of two statements.
Subclass pybasic conversions for semantic transform.
Some dense linear algebra bugfixes
Removing old fusion code.