Optimal binning seems to work

Many bug and typo fixes, that should do the trick now. A few notes on how to
improve:

1)  Apparantly this method can only handle RMFs from OGIP files. No slang
    functions, no C-modules ( find a way to access the in-memory RMF)
2)  Since the algorithm works on the data, it is necessary to "reset" the
    binning, read: We rebin on the original grid and then perform the work
3)  If it is impossible to access the in-memory RMF, add try-catch statements
    to return an error instead of just dying.