Sometimes AB converts stimsets with custom waves to third party stimsets on load from PXP or fails to load these stimsets entirely

[MichaelHuth]

Error:
When stimsets with custom waves were loaded through the AB then only the already saved stimset wave and not the parameter waves + custom wave was loaded.

• This converted this stimset to third party
• If originally only the parameter waves and custom wave existed in the PXP then it failed entirely

Diagnosis:
AB_LoadWave expected exactly one wave to be loaded after a call to
AB_LoadDataWrapper that loads waves recursivley in all sub data folders
If in a sub DF wave(s) with the same name template existed then
these were loaded too.
While the loaded waves contained the intended wave, the result was
rejected.