Studio often crashes when importing multiple presentations at once

Create empty presentation, import 10+ presentations at once. Import the same 10+ presentations at once again -> usually crashes.

Some of the presentations I used have other imported presentations as subpresentations, which may be relevant.

The issue seems to be related to RegisterSubpresentations(), where QCoreApplication::processEvents(); is called. This probably leads some events getting handled in wrong order. The import of multiple .uips is handled by just loop-importing single uips, which leads to a lot of unnecessary rewriting of the .uia and a lot of unnecessary registrations of subpresentations. The .uia file update should be batched and done once.