In (~and p1 p2), a failure in p2 now always dominates a failure in p1.
Consequently, if a pattern succeeds, its failures don't matter.
Add {pat,hpat,action}:ord wrappers, ord prframes. Apply ordering to
main pattern and side clauses. Add better progress analysis to
eliminate order wrapping.
This is a partial solution to the ~and problem, only for side clauses.
In (~and p1 p2 p3), one often wants errors in p2 to take precedence over
errors in p1, and likewise for p3 over p2. One solution is ~commit, but
that prevents backtracking. Another is ~post, but then two ~post wrappers
are needed around p3. Also, it doesn't make sense to compare progress of
the third #:with clause from stxclass A to the second #:with clause of
stxclass B and say third beats second.
So, generalize 'post to (post group index); post frames are comparable to
each other only if group is the same, then compared by index. (Post still
beats CAR and CDR.) Each set of side clauses shares a group.
For simplicity of code generation for now, use gensyms to identify groups.
