Input parser specific for fasta quality files

I noticed a bug in `cogent.parse.fasta.MinimalFastaParser` when parsing an old style quality file that were split across multiple lines such as:

\>identifier
10 12 13 14 15 20 30
34 41 21 30 12 10 11

what occurs is that the last qual score of a line and the first qual score of the next line get merged together such that the output looks like the following:

\>identifier
10 12 13 14 15 20 **3034** 41 21 30 12 10 11

to overcome this I've added in a new parser into `cogent/parse/fasta.py` specific to fasta quality files that returns the desired output