Fix #1609, fix #1628 - Revert #1397 (#1700)

When transmitting data in a HTML-encoded element like <content type="html" />,
relying on newlines being preserved is not wise, since HTML by itself
does not care for newlines - it cares for <p> and <br>

Additional fix: reset NSFW toggle after sending toot

app/assets/javascripts/components/reducers/compose.jsx

@@ -67,6 +67,7 @@ function clearAll(state) {
     map.set('is_submitting', false);
     map.set('in_reply_to', null);
     map.set('privacy', state.get('default_privacy'));
+    map.set('sensitive', false);
     map.update('media_attachments', list => list.clear());
   });
 };