added ghc-options to bitcurry.cabal
added TODO in Bencode.hs: ensure that only a - sign is accepted for bencoded integers; currently + is also accepted, which is not in the specification
added TODO: check sha1 library for a binary instead of hex encoding, possibly obviating need for ultra-hacky encodePercents helper
first draft of quickCheck based testing of Bencode! added Arbitrary instance for BL.ByteString which only generates bencoded values; wrote perhaps featureful version of prop_bytestring_inverse and draft of prop_bencode_inverse; prop_bytestring_inverse tests pass