* thunar-vfs/thunar-vfs-update-thumbnailers-cache.c: Add ability to
	  load custom thumbnailers from .desktop files. Drop the hardcoded
	  font thumbnailer.
	* thunar-vfs/thunar-vfs-font-thumbnailer-1.desktop.in,
	  thunar-vfs/Makefile.am: Install a .desktop file for the font
	  thumbnailer.
	* docs/manual/, po-doc/: Update the user guide with detailed information
	  about the custom thumbnailers.


(Old svn revision: 24227)