Add to CutTrim, trim to length from 5' or 3'

[msettles]

Need to trim 2 libraries/run to the same length, can be variable cut, can do so now by specifying CutTrim early with a specific trim, however 1 library has to be trimmed 0 length, so that CutTrim is in the result (needed for MultiQC) but doesn't actually do anything.

In this case a better resolution would seem to be to add 2 new parameters to Cut to length (from 5' or from 3') rather than to cut specific length. So example
hts_CutTrim -p 150 ..... | <-- Trim from the front so that the final size is no larger than 150
hts_CutTrim -q 150 ..... | <-- Trim from the back so that the final size is no larger than 150

This functionality doesn't exist elsewhere