Add multiple trimmed fastq file types to fastq artifact

[tanaes]

After trimming, we can conceivably have four fastq file types derived from a single original read pair:

• Trimmed forward reads with surviving reverse mate pairs
• Trimmed reverse reads with surviving forward mate pairs
• Trimmed forward reads without surviving reverse mate pairs
• Trimmed reverse reads without surviving forward mate pairs

Each of these read types would be useful to track independently for downstream applications -- for instance, in assembly or read mapping, type 1 and 2 above will frequently need to be provided in a set, while type 3 and 4 might optionally be concatenated and provided as independent single-ended reads.

Another scenario, when I'm doing HUMAnN2, I typically ignore reverse pairs altogether and only analyze Type 1 and Type 3 forward reads after trimming.

Suggest following names:
forward_trimmed_paired
reverse_trimmed_paired
forward_trimmed_unpaired
reverse_trimmed_unpaired