Pre-process mixed-case words for synthesizers that don't handle them correctly

[joanmarie]

I recently removed the pre-processing of mixed-case words (e.g. "HelloWorld") from Orca because from my testing the synthesizers were already doing this work, so there was no need for Orca to do it.

End user testing has revealed that there are a few which do not, such as voxin with IBMTTS. Therefore, would it be possible for speech-dispatcher to do this work at least in the case of no-longer-maintained synthesizers?

[sthibaul]

We can probably implement a shared helper for this indeed.