Add tests to FixedSizeCodecTest

tests did not actually pad nor prove round trip works when padding
ascii is suboptimal combinator since its encode/decode behavior is
asymmetrical
functional encoding
Add tests to FixedSizeCodecTest

tests did not actually pad nor prove round trip works when padding
ascii is suboptimal combinator since its encode/decode behavior is
asymmetrical

pad fixed size with a codec
fix conflicts
report paddedCodec failure using \/

only encode paddedCodec if needed

only encode paddedCodec at most once per using codec encode
Merge pull request #24 from searler/fixed_pad_branch

Add padding via codec to fixed size codecs