Quick search for only one criteria

[mtotschnig]

With the new Search UI introduced in 3.9.4, searching for a single criteria needs one additional step (confirmation of the dialog). Users suggest to make quick searches again possible without having to confirm. There are several options for streamlining single-criteria searches:

1. In parallel to the new Search icon opening the Filter dialog, bring back the previous search menu, allowing to define searches for single criteria
2. When the filter dialog opens, open the UI for the last used criterion automatically.
3. Add a checkbox to the filter dialog, that would switch between single and multi-criteria modes.