Python API. Rename onDatabaseUpdated and onDatabaseScanStarted

If my understanding of these two methods is correct they have nothing to do with databases or anything being updated, but are exactly the same as `OnScanStarted` and `OnScanFinished` in the JSON-RPC API. I have no idea why they were named like this or why the documentation says what it says. Judging from the forums it's already causing a lot of confusion.

This is more a proposal than anything because yes, it will break existing add-ons using these methods.

The first commit contains only corrects to the documentation in case that's a 'no'.