Bytea backend to native hex format decoder

Optimize the hex format decoder to work directly on the byte[] backend data.
Fix bug causing output byte[] to be one extra byte in length.
Bytea backend to native escape format decoder

Optimize the bytea escape format decoder to operate directly on the byte[].
Fix bug in escape format encoder (missing digit 7 in the lookup array).
Merge pull request #59 from glenebob/bytea_backend_text_decoder

Bytea backend text decoder