Fix examples/machine-code/garbage-collectors for tight equality

Finish fixing machine-code for new by

build --selftest=3 now completes; I'm ready to merge into master.

Build more machine-code example thys with pat_assum

Remove trailing whitespace in source files.

I've changed the way tail-recursive functions are defined.
They are now defined based on a step function:

step: 'a -> 'a + 'b

Tail-recursive functions loop until their step function
returns something in the right component (INR).

A general update.