libgd: Added libgd to cut-n-paste

A separate commit where libgd is added to cut-n-paste. libgd is used for the bookshelf
view of recent documents.
evince: Added bookshelf view for recent documents.
evince: Updated implementation of bookshelf view

Updated as per Jose's comments on the bug report.
bookshelf: Save thumbnails and metadata

Partly implemented switching between document and bookshelf using a
button.
Some minor improvements.
bookshelf: Use gtk_recent_info_get_modified from now on

Use gtk_recent_info_get_modified instead of
gtk_recent_info_get_visited for ordering the recent items.
bookshelf: Add files to bookshelf only if they exists

Use gtk_recent_info_get_exists to ensure that the items added to
the bookshelf exist.
shell: Use toggle_button to switch to the bookshelf

It seems more natural as we 'toggle' between the bookshelf the
currently open document.

Also fixed sensitivity of the button when Evince is loaded without
a document.
bookshelf: Changed blank translatable srings to regular blank strings

This was done in response to KaL's observation that using _(""), ie,
blank translatable string is not correct and causes problems.
bookshelf: Construct the bookshelf before using it

Fix critical warning. It was trying to use the scrolled window
before it had been constructed.
shell: Rename class from EvBookshelf to EvRecentView

EvRecentView sounds more appropriate based on feedback with
KaL.
toolbar: Changed Bookshelf/RecentView button back to a normal one

Previously, this button had been changed to a toggle button. Now,
since a different toolbar will be displayed with the bookshelf/recent
view, it makes more sense for this to be a normal button.
shell: Implement a different toolbar for bookshelf/recent view

Added a new EvMinimalToolbar which is displayed while in
bookshelf/recent view, instead of the full regular toolbar.
ev-recent-view: Remove unused get_property and set_property
ev-window: Removed the recent menu list

Since we have EvRecentView now, there is no use of the menu of recent items.
Removing it.
ev-recent-view: Don't show 'author' in recent items view

Removed this based on jaliste's suggestion in IRC.
ev-recent-view: Fix coding style
shell: Implement EvToolbar as an abstract base class

EvRecentViewToolbar and EvMainToolbar can inherit from EvToolbar.
ev-recent-view: Rename list_store to model
ev-recent-view: Change 'self' by 'ev_recent_view'

Make the code conform Evince convention to name objects