Modify strings for preferences, add attribution to map

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Preserve tile cache when Activity is recreated

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Style map reattach button

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Display stale locations in gray in Map view

Allow switching the style of map overlays on the fly
Central method to assign style to location provider if it is missing
Methods to mark locations as stale and identify locations marked as stale
Ignore stale locations when recentering map

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Move stale locations in view when only stale locations are available

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Remember map position and zoom

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Handle map redraw operations properly

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Reliably redraw map on update

Signed-off-by: mvglasow <michael -at- vonglasow.com>
Rearrange code to (re-)create map overlays

Signed-off-by: mvglasow <michael -at- vonglasow.com>