Store IfExtNames for PatSyn matchers and wrappers in interface file
Fold mkPatSyn{Matcher,Wrapper}Id into TcPatSyn
Reconstruct patsyn type from matcher type
Pattern synonyms have no implicit Ids
Move comments around and re-factor psTheta

Cosmetic changes only in here.  The only significant
change is splitting psTheta into two fields
Comments and tracing only
Update Haddock to new PatSyn representation