Hack: ignore filename for path equality

[AlanDrake]

This is somewhat of a hack in order to be able to see/exclude pictures from a specific directory. It feels more natural, since the file path uses a directory as a filter by default.

Could be otherwise implemented by upping schema version and saving another column for directory path in db, but it's more duplicate data, and would prevent going back.

The rationale is that the file path filter is used to filter directories, a common user may not even imagine it's the full path and would be confused that they can't filter the current directory by simply choosing "Equals".

Potentially a solution to #398

There could be an option to choose if to default to "Starts With", or "Equals" when opening a folder.