Implements #2234: Hide own/found from Live Map

Added a button to show/hide own/found caches in the Live Map menu, under
the "Map settings" option (renamed from "Map modes").

Refactored boolean "liveChanged" in CGeoMap.java, renamed to
"markersInvalidated" as it now has more than that one use.
Added fix suggested by rsudev

Resolves the problem of caches sometimes not displaying when switching
from hide to show (if they hadn't previously been loaded).
Merge pull request #3030 from culmor30/issue-2234

Implements #2234: Hide own/found from Live Map