change to explicit continuation-return implementation
remove monad request continuation from iteratee
bugfix: sequence_ now works
implement group,groupBy
clean up build warnings
implement parI
tests: add parI property
Iteratee.cabal: require cabal-version>= 1.10
parI: add code for a missing case (EOF (Just e))

also fix some build warnings in Data.Iteratee.Parallel.hs
remove more Functor constraints from some ListLike functions
add traceContIteratee and traceContEtee
Change the type of EnumerateeHandler

There was a bug in eneeCheckIfDoneHandle where certain returned exceptions
weren't handled.  In order to fix this, it's necessary to be able to handle
exceptions from the outer iteratee, not just the inner iteratee.  Converting
exception handlers shouldn't be too difficult as an inner iteratee can just be
wrapped in 'return' to lift it to the outer.

This also fixes some bugs in eneeCheckIfDone* where the recovery continuation
wasn't set properly.
add traceEteeExc
PTerm: update so that the outer iteratee state reflects inner state

After sending EOF to the inner iteratee, the outer iteratee should be in the
same state, e.g. if the inner iteratee returns a ContMore, the outer iteratee
should also be ContMore.
tests: add tests for standard and nested seeking
clean up comments
benchmarks: fill out .cabal file so they actually work
bugfix: convStream* now checks for the stream state after recovering from exception
Data.Iteratee.roll - fix logic error

This fixes the same problem as #eaa16cc, but the branches have diverged enough
that cherry-picking that merge is real pain.
ListLike.filter: use mapChunks instead of convStream

Some null chunks may be passed through now, but mapChunks is much nicer on the
optimizer.