Accessibility fixes

- Aria landmarks
 - Title attributes to all icon only buttons
 - <Multibutton/> now internally a radio group
 - Replaced 1 'skip navigation link' with UI group links
 - Added map specific shortcuts to the shortcut menu
 - Hidden layer list actions from tab index

src/components/map/OpenLayersMap.jsx

@@ -179,6 +179,8 @@ export default class OpenLayersMap extends React.Component {
       <div
         className="maputnik-ol"
         ref={x => this.container = x}
+        role="region"
+        aria-label="Map view"
         style={{
           ...this.props.style,
         }}>