libview: Make the caret cursor movements relative to the selection

 * Right/left arrow: Position the cursor in the start/end
   boundaries of the selection.
 * Up/Down arrow: Position the cursor one line before/after the
   start/end boundary of the selection.
 * <Ctrl>Right/left arrow: Move by word as it the cursor were in
   the start/end boundaries of the selection.
 * Home/End: Move to the beggining/end of the line containing the
   start/end boundary of the selection.

Fixed also the equivalent selection commands (+<Shift>)

https://bugzilla.gnome.org/show_bug.cgi?id=704631
Revert "libview: Make the caret cursor movements relative to the selection"

This reverts commit 1141042bd051d0e1ccca349dc0c0c35a2791c775.
page-action-widget: Reduce the size of the page label for documents with special page labels