* Conversation List Item: timestamp bold only when convo has unread
* Preserve the positioning of overlays on re-entry into convo
* ConversationListItem: Handle missing and broken thumbnails
* Shorten timestamp in left pane for better Android consistency
* Update convo last updated if last was expire timer change
But not if it was from a sync instead of from you or from a contact.
* Make links in quotes the same color as the text
* MediaGridItem: Update placeholder icon colors for dark theme
* Ensure turning off timer shows 'Timer set to off' in left pane
* ConversationListItem: Show unread count in blue circle
* Add one pixel margin to blue indicator for text alignment
* Ensure replies to voice message can bet sent successfully
Biggest changes forced by this: alt tags for all images, resulting in
new strings added to messages.json, and a new i18n paramter/prop added
in a plot of places.
Another change of note is that there are two new tslint.json files under
ts/test and ts/styleguide to relax our rules a bit there. This required
a change to our package.json script, as manually specifying the config
file there made it ignore our tslint.json files in subdirectories
