Add direct message tab.

src/components/dm_timeline/dm_timeline.js

@@ -0,0 +1,14 @@
+import Timeline from '../timeline/timeline.vue'
+
+const DMs = {
+  computed: {
+    timeline () {
+      return this.$store.state.statuses.timelines.dms
+    }
+  },
+  components: {
+    Timeline
+  }
+}
+
+export default DMs

src/components/dm_timeline/dm_timeline.vue

@@ -0,0 +1,5 @@
+<template>
+  <Timeline :title="$t('nav.dms')" v-bind:timeline="timeline" v-bind:timeline-name="'dms'"/>
+</template>
+
+<script src="./dm_timeline.js"></script>