Switch to correct input files

[ns-rse]

I've been using the wrong input files and have mistakenly used those that go in to the start of the pipeline not those
that are produced by the various earlier stages. Although slightly confusingly the all_introns_counts_and_info.py
regression test does actually produce output without these earlier steps.

• Switch to correct files post earlier steps.
• Update regression test.
• Switch to new files in tests/contest.py and update tests/test_isoslam.py.