Make TorrentTreeView a part of UI XML
Fix build
De-deprecate -gtk
Merge remote-tracking branch 'origin/wip/ui-rewrite' into wip/looks-familiar

Conflicts:
	assets/mainwindow.ui
	src/gtk/GtkFileTreeView.cpp
	src/gtk/GtkMainWindow.cpp
	src/gtk/GtkTorrentTreeView.cpp
	src/gtk/GtkTorrentTreeView.hpp