action to group proof steps into ProofSeq or ProofDecor (for single)
removed old Z/EVES implementations of ProofProcessPage

All functionality has now been replicated in the generic PProcessPage in pp.ui
better icon for ProofDecor
cleanup old
better icon for attempt
better icons for CZT terms
better label rendering for ProofElem

Listening to changes in ProofInfo and firing notifications to update ProofElem label
use just "info" for proof info labels
Merge branch 'master' into group-steps
ungroup steps action
Merge branch 'group-steps'