Update tests, fix warnings and dependencies, upgrade to conduit-0.5.0

[mkscrg]

• Update the tests to use a test-suite section for the unit tests and an unbuildable-by-default executable for the benchmark. The benchmark takes the input filename as a command line argument. The tests are compiled and run with:

  cabal-dev install --enable-tests

  The benchmark is compiled and run with:

  cabal-dev install -f bench
  ./cabal-dev/bin/bench

• Fix warnings from all source files.
• Remove unused dependencies from the cabal file: directory, safe, transformers, unix-compat.
• Put all pragmas in source files, remove unnecessary pragmas from cabal file.
• Upgrade to conduit-0.5.0. Specifically conduitState StateProducing and sequenceSink are no longer exported by Data.Conduit. These are replaced with simple usage of await and yield.

[mkscrg]

Added another commit that makes use of the generalized Pipe types, per the recommendation in the conduit Haddocks: http://hackage.haskell.org/packages/archive/conduit/0.5.0/doc/html/Data-Conduit.html#g:8

Sorry for the suddenness of these contributions. I wanted attoparsec-conduit-0.5.0 compatibility for some data processing work, and it snowballed a little.