MapWidget.qml: create an instance of MapWidgetHelper

This instance in the QML code itself will be accessed by both the
mobile and desktop version. That way, the map code between
the two Subsurface versions will be shared.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>

mobile-widgets/qml/MapWidget.qml

@@ -1,6 +1,7 @@
 import QtQuick 2.0
 import QtLocation 5.3
 import QtPositioning 5.3
+import org.subsurfacedivelog.mobile 1.0
 
 Item {
 
@@ -11,6 +12,10 @@ Item {
 		name: "esri"
 	}
 
+	MapWidgetHelper {
+		id: mapHelper
+	}
+
 	Map {
 		id: map
 		anchors.fill: parent