Trailing whitespace in the amplicon sequence is not tolerated

[martinaryee]

Feature request: Trim trailing whitespace in amplicon field (Column 2) of amplicon file.

Background: I sometimes get the following error when running CRISPRessoPooled in amplicon mode:

ERROR: The amplicon sequence 4-11873390-11873412 contains wrong characters: 

It is related to trailing whitespace in the amplicon field of the amplicon file which seems to happen frequently in when Excel is involved in generating these files.