Significant and compatibility-breaking changes.

Version 0.3:
	- Removed 'flatStrict' and 'unflatStrict' (use 'flat' and 'unflat' instead that also encode/decode strictly)
	- `unflatWith` now takes a decoder for the unpadded value (previously it expected a padded decoder) and decodes the padded value
	- Added some decoding primitives
	- Added Data.ByteString.Convert
