Hidpi

A first go at updating the actions icons for hidpi support. There should be very few differences under normal dpi except for the addition of a few icons that were missing in the theme and now have matching versions instead of falling back to the gnome icons. The biggest change is that under hidpi toolbar and menu icons should be much more consistent with the normal dpi versions and give clean and proper icons.

More could probably be done here. May need to add some additional sizes such as 96px and at some point and it would probably be a good idea to add our own set of matching symbolics eventually instead of relying on whatever the gnome theme provides.