Add navigation overlay

[M4rtinK]

Add navigation overlay, on top of the map screen & hide compass when navigation overlay is active.

The overlay should certainly display:

• description of next turn/maneuver event
• distance to the next event
• next even icon
  • Mapbox icons could be used for this (Poor Maps are already using them)

Other optional data that could be displayed on the overlay:

• total & remaining route length
  • as distance
  • as time
• current event number / total events

For now lets just show the primary information on the overlay.

Data on the overlay can react to landscape and portrait changes like some modRana pages already do:

• portrait is one column
• landscape is two columns

Clicking the overlay should probably show a page listing all route events & additional options (reroute, clear, etc.). It could also host the addition information about the route.

Enabling and disabling the navigation mode - with simple routing:

• with a "navigate" button that shows up once a route is found
• once the navigation mode i enabled the routing buttons should be hidden
• to turn off the navigation mode use a "stop navigation" button, displayed where the routing buttons would normally be

With advanced routing (once implemented) the navigation mode would be offered to the user once a route is found.

[M4rtinK]

So this should be now implemented in modRana, covering most of the points mentioned above.