remove unneeded dependencies, add a faint hint of testing

It looks to me like neither the 'io' nor the 'set' package are actually required to make this package fly. This pull request removes those dependencies from the code and from the info.rkt deps list.

Also, this translates a commented-out block of "this should parse" semi-tests into an uncommented block of "this should parse" semi-tests. There's still no expected results for these guys.