add option to FASTA reader to ignore blank/whitespace-only lines

[jairideout]

Would be useful to add an option to the FASTA reader to ignore blank/whitespace-only lines.

[ebolyen]

👍

[ebolyen]

Had this issue earlier this week actually.

[jairideout]

This change should happen with the FASTQ parser too.

[ebolyen]

Some unit tests that definitely should exist for this functionality:

• The case where an empty line occurs in the middle of a record should fail
• The case where an empty line occurs instead of the sequence should fail
• The case where an empty line occurs inside of a sequence block should fail (same as: a stranded sequence without an identifier should fail)
• The case where an empty line occurs between records should succeed

[ebolyen]

@anderspitman Would you be up for tackling this issue? Should be relatively straight-forward and will introduce you to IO. I am happy to explain anything in regards to IO as well.