Testing of transforms is unclear and overengineered

[thejayps]

Transforms test in ztfm.c (at the time of writing, in branch #214) lacks clear comments for most of the code, contains unused code, and contains a somewhat overengineered parser (which may be useful to develop elsewhere as part of test infrastructure). This, in addition to combining many test cases into one function, makes the file very long and difficult to understand and review.

We should re-design the testing of transforms.

Fixing this issue may provide a solution to #243

[rptb1]

See also 0b27a6c59