Data for PSP generation created as follows; a few extra examples are supplied
over and above those run using make test.

For make test:
1. DNA: positive file one-peak-dna.fasta, negative file all-A.fasta
   produce psp-gen/one-peak-dna-revcomp.psp
2. protein: postitive file one-peak-protein.fasta, negative file all-A.fasta
   produce one-peak-protein.psp
See command lines below (as well as in scripts/metatest.pl).

DNA fasta files edited by hand, representing a case where there is a
single sequence of 10 Gs at the end of a single sequence preceded by
90 As, and another sequence of 100 As: one-peak-dna.fasta

The "negative" DNA set is all As (all-A.fasta).

Test cases are generated from this data as follows:

DNA:
psp-gen -pos one-peak-dna.fasta -neg all-A.fasta -revcomp > one-peak-dna-revcomp.psp

The DNA example tests:
* a single strong peak in the positive set not in the negative set
* scoring both strands

protein:
psp-gen -pos one-peak-protein.fasta -neg all-A.fasta -alpha prot -maxrange -triples > one-peak-protein.psp

The protein example again should only have one peak. However using
triples should widen it relative to the DNA example.
