Port to GTKLISTVIEW
Read commits. But basically mvoe progressive state into Mobject, use bind/unbind instead.
There are issues I wasn't able to solve even after a lot of work: adding extra items causes the items-changed signal to freeze GTK for about a second or slightly less, I can't figure out how to improve that performance even more. (Also, it seems to rebind all rows when that signal happens).
Some scrolling issues that are upstream issues.
I also added a new preference to disable link previews
However I think we should merge now.
Closes #11 (closed) #13 (closed)