Removed the unnecessary Builder import
Removed `pipes-parse` specific bits

I will reintroduce these back using the new `pipes-parse` idioms later
Removed `hiding (foldl')` since the Prelude doesn't export `foldl'`
Removed 'init' since it is inefficient

The efficient version requires using `pipes-parse` idioms, but I'm still
not sure it's worth reintroducing later.
Upgraded code to use latest `pipes-4.0` build