Get a clean working directory before testing filters.
Seeing what happens when you add a modified file that's already being tracked.
Will modifying test.txt break things?
Will modifying cookie break things?
Adding files that have been tracked triggers multiple clean filters.
Ignore soapy.
Soapy is a two-liner. The complexity of the filter seems not to matter.
Ignore grungy.
Test the smudge filter.
Add .gitattributes if it doesn't already exist. Closes #9.