Use proper super call in MismatchError.
We no longer need to handle string exceptions in TestCase.
Remove trailing whitespace.
We no longer need to handle Python 2.4's KeyboardInterrupt specially.
Remove and relocate some now un-needed compatibility functions.
Remove another Python 2.4 special case.
Remove (always skipped) test for string exceptions.
Remove Python 2.4 deprecation warning special-casing.
Don't support Python 2.4 test method naming.
Use a context manager as suggested by a comment.
Revert "Workaround 2.4 threading bug in test_spinner."

This reverts commit ba8af964e7e2b7378e21874c4383870b82bd1599.
Remove documentation suggestion that we support anything older than 2.6.
Remove workaround for getincrementaldecoder not being in 2.4.
Use super correctly.
Use explanatory functions for gnarly exception handling logic.
Add NEWS entry for Python 2.4/2.5 code path removal.
Merge pull request #71 from OddBloke/python24_25_removal

Remove Python 2.4/2.5 workarounds (OddBloke)