Finish new Message component, integrate into application

Also:
- New schema version 8 with video/image thumbnails, screenshots, sizes
- Upgrade messages not at current schema version when loading messages
  to show in conversation
- New MessageDetail react component
- New ConversationHeader react component

ts/components/conversation/TimerNotification.md

@@ -0,0 +1,39 @@
+### From other
+
+```jsx
+<util.ConversationContext theme={util.theme}>
+  <TimerNotification
+    type="fromOther"
+    phoneNumber="(202) 555-1000"
+    profileName="Mr. Fire"
+    timespan="1 hour"
+    i18n={util.i18n}
+  />
+</util.ConversationContext>
+```
+
+### You changed
+
+```jsx
+<util.ConversationContext theme={util.theme}>
+  <TimerNotification
+    type="fromMe"
+    phoneNumber="(202) 555-1000"
+    timespan="1 hour"
+    i18n={util.i18n}
+  />
+</util.ConversationContext>
+```
+
+### Changed via sync
+
+```jsx
+<util.ConversationContext theme={util.theme}>
+  <TimerNotification
+    type="fromSync"
+    phoneNumber="(202) 555-1000"
+    timespan="1 hour"
+    i18n={util.i18n}
+  />
+</util.ConversationContext>
+```