Description

This pull request converts the MapScreen and WaypointCreationScreen UIs to use NUI.

Testing

Start a new game or continue an existing one.
Open the map screen (either using the Map button or by pressing the Tab key).
Try zooming-in by scrolling the mouse wheel forwards.
Try zooming-in by clicking the Zoom In button.
Try zooming-out by scrolling the mouse wheel backwards.
Try zooming-out by clicking the Zoom Out button.
Pan the map by holding the left-mouse button on it and dragging the mouse in the desired pan direction.
Waypoints
The waypoint creation screen should be displayed when the Marker+ button is pressed and a position chosen.
The three sliders on the waypoint screen should be adjustable from 0 to 255.
The colour shown at the top of the waypoint screen should correspond to the chosen slider values.
Clicking Cancel should not place a waypoint.
Clicking Done should place a waypoint.
The placed waypoint should contain the colour chosen.
Clicking the Marker- button and then selecting a waypoint should remove that waypoint
Visual/Scale Testing
Try to view the screen on different form-factors and screen resolutions. Android builds will not see as significant a difference here because they use automatic screen scaling based on the reported display density.
Elements should not be significantly overlapping.
Text should ideally not be wrapping mid-word.
Buttons should be large enough to be confortable to reach on Android.

This depends on #664.
This supercedes #642.
This should help with #563.
The colour selection has been changed from a scale of 0-1 to 0-255, since I felt that people would be generally more familiar with the 0-255 scale.