grilo: Remove unused "New" button
grilo: Fix possible crasher with no mtime

Fix crash when mtime isn't set for particular GrlMedia.
grilo: Hide back button when in search
grilo: Fix coming back from search

And reset to the root
grilo: Add main toolbar UI file to dist
grilo: Use GResource for grilo.ui as well
grilo: Reorder buttons on the header bar

To match gnome-documents:
- Search then select, Cancel replaced select button
- Rename "Done" to "Cancel"
- Remove "suggested-action" class from Cancel
grilo: Align function parameters
grilo: Set the number of selected items
grilo: Add selection menu to the toolbar
grilo: Disable Ctrl+A when not in select mode
grilo: Remove unused "search button" member
grilo: Add title/subtitle properties to toolbar
grilo: Coding style fixes
grilo: More coding style fixes
grilo: Show title when browsing
libgd: Another bug fix
grilo: Add a TODO item
grilo: Blacklist sources by prefix

So that grl-upnp can eventually be blacklisted and the dleyna
source used instead.
grilo: Pass model to be used to browse()