typo--
if it compiles, but don't reach the right state, save the right error message (fix #213)
fix detection of passed exercises

The totalTest is -1 when it does not compile, actually
remove the marker that an exercise was passed if it's failed after being passed
Cleanups in the ExecutionProgress class

- rename field "detail" into "executionError"
- Add a field "outcome" so that it's computed only once from the test
  counts. At least one useless code location was getting it wrong.
- make one more string as translatable on my way
- mark a bunch of methods that will soon die as "unchecked" to silence
  eclipse a bit
20140905: Release 2.4.1

  Soon in production, last chance to iron out the bugs found on time.

  * User Interface:
    - Students can explain their problem in a phrase when requesting
      for help (contributing to #208, but the teacher cannot answer yet)
  * Engine:
    - Save the error message also when it compiles but diverges (fix #213)