The new widget for the history keeps track of the the messages in the
list, therefore it can update a message and how a message is displayed
It also adds lacy loading of a new message batch or cached messages (not
yet in use)
This adds a new file called uitypes which contains a new struct which
holds all information needed to display a message in the message
history.
Also AppOp is removed from the message widget and the widget was
refactored to use the new uitype
We are moving away from the appOp therefore this removes it form the
message_menu. Also the use of different gtk:builder to load .ui files is
the better way.
This patch adds a new button to the main window to show the stickers. A
popover is shown when you click in this new button with all the stickers
group.
If you've purchased the stickers you'll view all the stickers there and
you can click over one sticker to send it.
Stickers not purchased are shown as a preview thumbnail and description
and a button to add is there too but not working yet.
