Revert "Introduce bool method testing whether or not distances were created correctly"

This reverts commit 115f98c9f3807a1225b701b8b8e6e0d34ef60f1e.
Going a different way with this.
Preliminary support for algorithms defining a tform on their RHS

Instead of :, ! can be used as a separator for algorithms that list a
transform defining a comparison against a fixed gallery, instead of a
distance.

Some things (e.g. training) are not really handled, but so far this works
reasonably well for untrainable gallery comparison transforms.