Support multiple having an eland file split into multiple fragments.

Support multiple having an eland file split into multiple fragments.
The interesting thing was changing the match_codes and mapped_reads
dictionaries into their own classes so I can add them together, and
it'll go through and add matching dictionary entries together.

e.g. MatchCodes({'U0':5})+MatchCodes({'U0':5}) == MatchCodes({'U0': 10})

Unfortunately because there are multiple samples per lane on the
hiseq this still isn't enough to support counting aligned results yet.