call status in message preview was isolated in a class and made prettier

src/widgets/call-status.jsx

@@ -0,0 +1,18 @@
+// The counter of unread messages in the topic.
+import React from 'react';
+
+// Props:
+//  incoming: true | false.
+//  success: true | false.
+export default class CallStatus extends React.PureComponent {
+  render() {
+    const icon2 = [['call_received', 'call_missed'],['call_made', 'call_missed_outgoing']]
+      [this.props.incoming ? 0 : 1][this.props.success ? 0 : 1] || 'question_mark';
+
+    return (
+      <div className="composed-material">
+        <i class="material-icons">call</i><i class="material-icons second">{icon2}</i>
+      </div>
+    );
+  }
+};