append_optdis_probe_or_si.py: sample_list is now a command argument
rather than a constant at the top of the code.

find_splice_location2.py: changed string 'all_probes_used' to
'all_probes' to make it the same format as find_slice_location.py

find_spliced_events.py: added a little comment.

read-write_gene_info.py: forgot to add sys.exit() after printing an
error message.
gitignore now ignores .sh and .txt files
Initial commit to visualize_optdis_results2.py: basically the exact same
as visualize_optdis_results.py but more flexible with samplelist input
arguments. Consider removing visualize_optdis_results.py because they
are so similar.