doctor: better quick option propogation for stats

* use contextmanager for quick stats instead of editing global state
  directly
* send quick to lots of stat related functions, so they
could possibly be used without doctor, if someone wanted to
* if a stats function has a 'quick' kwarg, send the value
there as well
* add an option to sort locations in my.time.tz.via_location

my/core/util.py

@@ -20,7 +20,7 @@ def get_stats(module: str) -> Optional[StatsFun]:
     # todo detect via ast?
     try:
         mod = import_module(module)
-    except Exception as e:
+    except Exception:
         return None
 
     return getattr(mod, 'stats', None)