Locale cleanup from the locale atlas

- An empty select "" carries no key=: the prompt keys go from the
  scenarios and from the locale files.
- Scenario option strings live only in scenarios_<lang>.properties; the
  duplicates in en/ru.properties are removed.
- English names/info for the map zones (mapzone/home, town_entry).
- locale/scenarios_ru.properties: Russian scenario strings get their own
  file next to scenarios_en.

locale/scenarios_en.properties

@@ -1,14 +1,10 @@
-home_outside/prompt = 
 home_outside/opt_enter = Enter the house
 home_outside/opt_town = To the town
 home_outside/opt_forest = To the forest
-town_entry/prompt = 
 town_entry/opt_home = Return home
 town_entry/opt_square = To the square
-town_outskirts/prompt = 
 town_outskirts/opt_home = Return home
 town_outskirts/opt_forest = To the forest
-vestibule/diner/prompt = 
 vestibule/diner/opt_workroom = To the workroom
 vestibule/diner/opt_dinerroom = To the dining room
 vestibule/diner/opt_bedroom = To the bedroom