FIX #1215: GHC fails to respect the maximal munch rule while lexing "qualified reservedids"
I didn't actually fix this to respect Haskell 98, instead I changed it
to follow the proposal for Haskell':
http://hackage.haskell.org/cgi-bin/haskell-prime/trac.cgi/wiki/QualifiedIdentifiers
Rationale:
- We didn't respect Haskell 98 with respect to qualified symbols either
- The Haskell' change makes things much cleaner
- Obeying the Haskell 98 spec literally has some unintended
consequences (e.g. M.where must lex as "M.wher" "e")
- Any programs that compiled before this change and do not compile
after it were illegal according to Haskell 98 anyway.