Fix -Wall warnings on Fixity.hs.
Fix some -Wall warnings on Extensions.hs.
Add lexWhile_ which ignores the return value.
Fix -Wall warnings on InternalLexer.hs
Fix -Wall warnings on annotated Fixity.hs.
Parse qualified record punning. Fixes #20.
Let RecursiveDo enable 'rec' keyword. Fixes #42.
Add test for #42.