Have fix_open subclass fix_file

That guarantees that any open-related scenario is fixed.

Closes #74
Greatly simplify fix_open

Use run ordering to prevent having to subclass.
Tweak a comment
Merge remote-tracking branch 'upstream/master' into fix_file_open
Drop the run order for fix_open

Because of the way the pattern has to be structured it is unnecessary.
Merge pull request #76 from brettcannon/fix_file_open

Have fix_open handle file()