Sort building levels recents by regular, then roof

The new building levels recent values is great. However, I've found that
the vast majority of the buildings in the areas I map are 4 values (1|0,
1|1, 2|0, and 2|1), so my recent values seldom change. As a result, a
stabler sort order is much easier for me to scan and find the entry I'm
looking for than the current FIFO queue, where they constantly re-order.

They are still added and removed in the same order; only the display
order is changed. So it has the drawback that you can't be precisely
sure which entry will disappear, after you add a new answer. In
practice, I think it doesn't matter that much.

Originally I tried sorting by total levels first, but when testing, I
found it harder to parse "1|1, 2|0, 1|2, 2|1" than "1|1, 1|2, 2|0, 2|1".

Unfortunately, the compiler can't figure out the type of `thenBy`
without the annotation.

app/src/main/java/de/westnordost/streetcomplete/quests/building_levels/AddBuildingLevelsForm.kt

@@ -31,7 +31,9 @@ class AddBuildingLevelsForm : AbstractQuestFormAnswerFragment<BuildingLevelsAnsw
     private val roofLevels get() = roofLevelsInput?.text?.toString().orEmpty().trim()
 
     private val lastPickedAnswers by lazy {
-        favs.get(javaClass.simpleName).map { it.toBuildingLevelAnswer() }
+        favs.get(javaClass.simpleName).map { it.toBuildingLevelAnswer() }.sortedWith(
+            compareBy<BuildingLevelsAnswer> { it.levels }.thenBy { it.roofLevels }
+        )
     }
 
     @Inject internal lateinit var favs: LastPickedValuesStore<String>