Toggle marker visibility with Ctrl+M

src/main.rs

                             Action::Nothing
                         }
                     },
+                    VirtualKeyCode::M => {
+                        if modifiers.ctrl {
+                            map.toggle_marker();
+                            Action::Redraw
+                        } else {
+                            Action::Nothing
+                        }
+                    },
                     VirtualKeyCode::H => {
                         if modifiers.ctrl {
                             map.toggle_atmosphere();

src/map_view_gl.rs

     ortho_tile_layer: OrthoTileLayer,
     atmos_layer: AtmosLayer,
     projection: Projection,
+    show_marker: bool,
     show_atmos: bool,
     last_draw_type: DrawType,
 }
             ortho_tile_layer,
             atmos_layer,
             projection: Projection::Mercator,
+            show_marker: true,
             show_atmos: false,
             last_draw_type: DrawType::Null,
         }
         };
     }
 
+    pub fn toggle_marker(&mut self) {
+        self.show_marker = !self.show_marker;
+    }
+
     pub fn toggle_atmosphere(&mut self) {
         self.show_atmos = !self.show_atmos;
     }
         match self.projection {
             Projection::Mercator => {
                 let ret = self.draw_mercator_tiles(cx, source, snap_to_pixel);
-                if !self.marker_layer.is_empty() {
+                if self.show_marker && !self.marker_layer.is_empty() {
                     self.draw_mercator_marker(cx, snap_to_pixel);
                 }
                 ret
             },
             Projection::Orthografic => {
                 let ret = self.draw_ortho_tiles(cx, source);
-                if !self.marker_layer.is_empty() {
+                if self.show_marker && !self.marker_layer.is_empty() {
                     self.draw_ortho_marker(cx);
                 }
                 if self.show_atmos {