add iterative/progressive fastqc vecscreen trimmomatic workflow

[rltillett]

As follows, more or less:

1. trimmomatic module IDs over-represented sequences
2. add polyNs (or polyN, length m minus k, where m=observed and k is chosen) to custom trimmomatic library
3. locally run blastn vs. univec using vecscreen-like mode
4. add hits to custom trim library and custom fastqc adapter/contam library
5. trim w/ just-made custom libraries
6. repeat if new vector found & added (always from original input files? might be best)

   Vecscreen mode

According to secret info I nabbed from ncbi

The VecScreen parameters are pre-set using blastn options: -task blastn -reward 1 -penalty -5 -gapopen 3 -gapextend 3 -dust yes -soft_masking true -evalue 700 -searchsp 1750000000000