requestRender

Schedule a single map-surface repaint (#80).

The underlying carto com.mapsted.map.views.MapstedMapView runs its GLSurfaceView in RENDERMODE_WHEN_DIRTY: a frame is only drawn when a redraw is explicitly requested (the native engine does this in response to input events and its own animations). A programmatic plot/camera update can therefore finish all of its data + camera work without a frame ever being scheduled, so the surface stays blank until the first user touch.

requestRender is thread-safe and draws exactly one frame, so calling it here is safe from any thread and does not cause continuous redraw.