screenshot: Fix error saving gallery save path
backend: Make cogwheel button square

https://bugzilla.gnome.org/show_bug.cgi?id=699237
grilo: Hide YouTube from browse for now
grilo: Show tracker contents in "Recent"

Instead of the recent files
grilo: Fix value of remaining

Don't set the address of the "remaining" variable as the number
of remaining items.
grilo: "Remaining" is a guint

GrlSourceResultCb returns the number of remaining items as
a guint so use that.
grilo: GdMainView already contains a scrolled window

So no need to put it in one already.
grilo: Load all the tracker videos on startup

Even if there's more than PAGE_SIZE videos.
grilo: Fix loading more items in channels