Bundling Enhancements

[russelldc]

1. When de-duping senders, if there are multiple emails from the same person and any are unread, then show as bold, if all are read then show as normal text. (reported by @jcgoble3, strategy by @abasiri) Done in commit fba8189
2. For a conversation with multiple participants, this extension always chooses the sender of the first message to display in the bundle author list. Inbox, however, displays the sender of the last message for read conversations and the sender of the first unread email for unread conversations, which is more useful. (reported by @jcgoble3)
3. Fix bundle flashing issue: insert a <style> tag and add the id of the email, then you can hide it properly. That way when gmail rewrites the tag for the emails and we lose the classes on it, it won't matter, it'll still be hidden. (strategy by @abasiri) Done in PR [#70] Prevent bundled emails from flashing/appearing in inbox #73
4. Reduce the opacity of a bundle's icon image if bundle contains no unread messages. As requested by @abasiri and @jcgoble3: I find that I want that to kind of fade to distinguish it from the unread ones better. Done in commit 897f9b6
5. Display unique icons (and respective font color for the label-link) for Gmail's built-in categories (Promotions, Updates, etc.) as seen in this screenshot of Inbox. These icons are now available in the images folder of the repo. Done in commit 0bad7b2
6. For custom labels, use their label color for the text color of the bundle's label-link and icon (it's an image, but might be possible with some CSS hackery). Done in commit ba984a4

The functionality listed below would likely require Gmail.js for reliable observers/event listeners:

7. Display a sweep all emails icon button on bundle row on mouse hover, clicking this would archive all emails contained in bundle that aren't pinned
8. Display a back button inside the bundle (search page), to return to the inbox
9. Clicking done on an open bundled email should return you to the bundle (search page)
10. If inside an empty bundle (search page), it should return you to the inbox (including if you clicked Done on an email in the list)

Found a bug:

11. If you start from a non-Inbox folder, like Snoozed or Done (refresh in that folder, or go direct to other folder's URL), then visit the Inbox folder, the bundles there won't have extra info like count and senders. After, if you go back to that original folder, you'll probably see bundles on that page when there shouldn't be.

[russelldc]

Fixed No. 1 in commit fba8189