[FEATURE] Map caching settings

[Korb]

I suggest adding a map cache limit and preferably a cache location (internal memory or memory card if available) to the settings. Accordingly, in this case, it should be possible to clear the cache without clearing other user data of the application, and use the cached data when re-accessing the same terrain at the same scale. This will speed up the display of the map, reduce mobile traffic, which is critical in areas with low Internet speed or its high price.