Add skeleton for bg maps window

qt/BackgroundMapForm.ui.qml

@@ -0,0 +1,33 @@
+import QtQuick 2.4
+
+Item {
+    width: 400
+    height: 400
+
+    Grid {
+        id: grid1
+        x: 0
+        y: 0
+        width: 256
+        height: 256
+        rows: 32
+        columns: 32
+
+        Rectangle {
+            id: rectangle1
+            width: 200
+            height: 200
+            gradient: Gradient {
+                GradientStop {
+                    position: 0
+                    color: "#ffffff"
+                }
+
+                GradientStop {
+                    position: 1
+                    color: "#000000"
+                }
+            }
+        }
+    }
+}