[l10n] Updated Catalan (Valencian) translation
Add a configure check for hi-dpi support

In order to support hi-dpi (GDK_SCALE) we need new-enough versions
of both GTK+ and cairo. Add a configure check for the appropriate
functions and define HAVE_HIDPI_SUPPORT.

https://bugzilla.gnome.org/show_bug.cgi?id=723431
ishell: Make the about dialog non modal
shell: Update website and copyright years in about dialog
shell: Move about dialog to the app menu and make it independent from the document
shell: Use a GtkHeaderBar instead of a GtkToolbar and window decorations

Based on patch by Yosef Or Boczko.

https://bugzilla.gnome.org/show_bug.cgi?id=711078
Revert "shell: Use a GtkHeaderBar instead of a GtkToolbar and window decorations"

This reverts commit c9127524e1409d582f038439e9143695d1fadc0d.

It broke the fullscreen mode.
recent-view: Verify a path exists before adding an icon

Fixes warnings when switching from the recent view to
a document back and forth.
recent-view: Use a GtkIconView and get rid of most of libgd cut-n-paste
recent-view: Allow to open documents from recent view with the keyboard
recent-view: Do not sort the GtkTreeModel

We already sort the recent items ourselves and everytime the recent
files change we clear and fill the model again.
shell: Make a class for EvToolbar to abstract for other toolbars
ev-recent-view-toolbar: Implement a different toolbar for recent view

Added a new EvRecentViewToolbar which is displayed while in
recent view, instead of the full regular toolbar.
ev-toolbar-main: Add recent view show toolbar button
ev-window: Integrate the recent view
ev-window: Removed the recent menu list

Since we have EvRecentView now, there is no use of the menu of recent items.
Removing it.