added gtorrent icon
Session state

See 579f947eec297f6c7afa702b44ce0075c4c0c29f
Please report bugs.
Merge branch 'master' into wip/savestate
Clicking in a blank zone of the treeview now deselects eveerything
Fixed bug where the graph was updated on a single click
Put the treeview in a scrolled pane.

Without it, the window had for its minimal height, the height of headerbar+columns height+(n_of_torrents * row height) + bottom panel.
settings.glade is now copied in the build dir
Fixed lag when selecting another torrent
Toggle the start/pause buttons

Depending on the selection, the buttons may or may not be visible.
update core submodule
set reasonable column widths by default
Better icons (on my theme at least)
Size and order of columns are now saved

I just realized that the resize mode is really weird, also it's not complete yet, I need to make it remember the hidden column.
Hidden columns are now memorized
Fixed bug where block graph wouldn't update
Fixes crash when saving the settings
merge
merge
merge
merge