Merge pull request #1 from Shimuuar/master

- Cabalized test suite
- Generic functions parameterized by element getter/putter
- Generic instance for unboxed & storable vectors
- Temporarily removed unsafe instance for storable vectors
Restored efficient Storable vector serialization code, and marked it
as unsafe with a warning about inter-host endianness/word length
issues. Added tests for both the safe Storable instance as well as the
unsafe functions.
documentation cleanup
Relax dependency on cereal