Required:
* Improve tile cache:
-** Use an intelligent algorithm to automatically try (async) updating tiles if they have a certain age
-*** If they have changed, possibly also try (async) updates of other cached zoom levels covering this area
-** Clear cached tiles option
-* Find the bug that messes up the display when panning on not fully loaded tiles (web connection down)
+** If cached tiles have changed, possibly also try (async) updates of other cached zoom levels covering this area
+** Pre-cache tiles in adjacent areas and possibly zoom levels
* Show a notification when we are loading tiles or saved data
* Display length and duration of track
* Display movement speed