Minor UI changes

Fixed the headerbar buttons that weren't square.
Made the popover leviate on the left to not overlay the torrent list
Made the File association dialog a part of the UI, it uses a Headerbar now.
Spawn file chooser in the middle of its parent
Fix crash in filetreeview when deleting torrents
Many changes

* Separate infobar in its own UI file
* Fix the window hanging when closing
* Run the GUI only after it was fully initialized
* Other I don't remember
add time divisions
change add to addValue to not shadow virtual function
Merge remote-tracking branch 'origin/wip/timed-graph' into wip/looks-familiar
Merge remote-tracking branch 'origin/wip/ui-rewrite' into wip/looks-familiar

Conflicts:
	assets/mainwindow.ui
	src/gtk/GtkAssociationDialog.cpp
clobber large chunks of code in a desparate attempt to make it build