Added application shortcuts and shortcut modal.

Also moved modals into App.jsx to move the business logic to one place.

src/components/modals/ShortcutsModal.jsx

@@ -0,0 +1,75 @@
+import React from 'react'
+import PropTypes from 'prop-types'
+
+import Button from '../Button'
+import Modal from './Modal'
+
+
+class ShortcutsModal extends React.Component {
+  static propTypes = {
+    isOpen: PropTypes.bool.isRequired,
+    onOpenToggle: PropTypes.func.isRequired,
+  }
+
+  constructor(props) {
+    super(props);
+  }
+
+  render() {
+    const help = [
+      {
+        key: "?",
+        text: "Show shortcuts menu"
+      },
+      {
+        key: "o",
+        text: "Open modal"
+      },
+      {
+        key: "e",
+        text: "Export modal"
+      },
+      {
+        key: "s",
+        text: "Sources modal"
+      },
+      {
+        key: "p",
+        text: "Source settings modal"
+      },
+      {
+        key: "i",
+        text: "Toggle map"
+      },
+      {
+        key: "m",
+        text: "Focus map"
+      },
+    ]
+
+
+    return <Modal
+      data-wd-key="shortcuts-modal"
+      isOpen={this.props.isOpen}
+      onOpenToggle={this.props.onOpenToggle}
+      title={'Shortcuts'}
+    >
+      <div className="maputnik-modal-section">
+        <ul>
+          {help.map((item) => {
+            return <li>
+              <code>{item.key}</code> {item.text}
+            </li>
+          })}
+        </ul>
+        <p>
+          <Button onClick={() => this.props.onOpenToggle()}>
+            Close
+          </Button>
+        </p>
+      </div>
+    </Modal>
+  }
+}
+
+export default ShortcutsModal