Relax the axiomatisation of prominence

[matentzn]

Currently we have this:

This causes some confusion as phenotypes with an abnormal prominence of something classify under abnormal position. I vote to simply move the prominence and protruding branches out from under position.

@dosumis @wdahdul @balhoff @sbello

[nicolevasilevsky]

what do you think the parent should be then? should it be a child of 'physical quality'?

I'll create a PR for this and tag the folks above.

[dosumis]

I'd keep superclass protruding, and move that under physical quality.