A few UI fixes/enhancements.

Changes:
* My autism was triggered by the fact that clicking in a blank area didn't deselect the torrents, so I changed that.
* The graph was updated in two case, once every second and when the torrent was clicked on, now the graph is updated only with the timeout.
* The more torrent you added, the bigger the minimal height of the window was, putting the treeview in a scrolled pane fixes this behavior.
* Changed the CMakeLists.txt files so it copies the settings.glade file in the build folder, so hopefully there'll be less people complaining about FileError, but we may want to find a way to embed in into the executable.
* The Infobar was updated only by the timeout, meaning that if you selected another torrent right after it was updated, you would have to wait up to one second until you see the changes.
* Changed the gay colored icons with their neutral symbolic counterparts so it fits better with the theme
* Removed the folder button that served no purpose
* The order of the columns, their size and visibility are now saved and restored through each session, see the comments in the source file for details on how it is saved