This collection is just an in-memory indexer used for typeaheads. For
display, the matching models are added to a separate collection. Thus,
the order of the elements in the typeahead collection does not matter.
It feels a little weird when you can't see the matching member. Would
consider putting this back in if we display the member list in the
contact list item view.
Previously, the ugly file input was hidden with opacity, and styled as a
square paperclip icon, but its drop and click zones were not constrained
to the visible square. They remained active across the whole 'Choose
File' button, which overlapped with the textarea. Instead, hide the file
input complete (display: none) and transmit click events from the
paperclip to the input programmatically.
Eventually, we'll need to address drag and drop events, but I want to do
that at the window level. Otherwise dropping a file outside the file
input drop zone causes the browser to navigate to the file://... url.
Render the entire conversation from a template, because some parts of it
must be rendered conditionally if it is a group vs private conversation.
Also apply some style fixes and restore lost functionality:
* Make conversation title bar fixed.
* Widens message bubbles.
* Unhide message list.
* Restore attachment rendering.
* Restore message sending and attachment file selection.
* Style attachments file input as a paperclip.
* Style send button like on Android and make it a submit input.
Don't auto open the last conversation. It doesn't make sense now that we
no longer have two column layout.
Don't trigger/listen for selected events. There's no need since the list
item opens a new popup now.
