main: Remove "drag motion" handling
main: Style fixes
main: Remove unused "Ask" dnd menu
main: Remove dnd support for the video widget

https://bugzilla.gnome.org/show_bug.cgi?id=703549
main: Add drag'n'drop support to the browser

https://bugzilla.gnome.org/show_bug.cgi?id=703549
main: Add dnd support to the "Recent" button

https://bugzilla.gnome.org/show_bug.cgi?id=703549
main: Don't allow adding directories to the recent view