This patch includes:
0) Typo in panic message. 1) prioritization of equalities over family equalities in the worklists. 2) rewriting of inert substitutions and solveds on-the-spot instead of kicking them out in the inerts. This required a monadic map over substitutions hence the modifications in UniqFM. 3) Just comments and removing stale commented code. 4) Useful SCC for simplifyInfer. 5) Making CoreStats outputable.