Add shortcut to toggle elevation chart

Press 'E' to show/hide the elevation chart.

index.html

@@ -910,6 +910,8 @@
                     id="elevation-btn"
                     aria-expanded="false"
                     aria-label="Toggle elevation chart"
+                    data-i18n="[title]footer.elevation-chart"
+                    title="Toggle elevation chart"
                 >
                     <span class="fa fa-area-chart"></span>
                 </button>

js/plugin/Elevation.js

@@ -7,7 +7,10 @@ BR.Elevation = L.Control.Elevation.extend({
             bottom: 30,
             left: 60
         },
-        theme: 'steelblue-theme'
+        theme: 'steelblue-theme',
+        shortcut: {
+            toggle: 69 // char code for 'e'
+        }
     },
 
     onAdd: function(map) {
@@ -30,6 +33,8 @@ BR.Elevation = L.Control.Elevation.extend({
             L.DomEvent.on(this._container, 'mouseup', this._dragEndHandler, this);
         }
 
+        L.DomEvent.addListener(document, 'keydown', this._keydownListener, this);
+
         return container;
     },
 
@@ -64,5 +69,11 @@ BR.Elevation = L.Control.Elevation.extend({
 
             layer.on('mouseout', this._hidePositionMarker.bind(this));
         }
+    },
+
+    _keydownListener: function(e) {
+        if (BR.Util.keyboardShortcutsAllowed(e) && e.keyCode === this.options.shortcut.toggle) {
+            $('#elevation-btn').click();
+        }
     }
 });

locales/en.json

@@ -42,6 +42,7 @@
     "ascend": "Ascend",
     "cost": "Cost",
     "distance": "Distance",
+    "elevation-chart": "Toggle elevation chart (E key)",
     "energy-per-100km": "Energy per 100 km",
     "hours": "hours",
     "hours-abbrev": "h",