Improvements to the LTSP Display Manager

The current LTSP Display Manager (ldm) uses a greeter written in pygtk using gnomecanvas. The loading of all the depending python modules makes the greeter application slow and memory hungry. To speed it up and make it smaller a new C/Gtk gui based on the code from https://launchpad.net/people/ogra/+branch/ltsp/ldm-greeter should get implemented. The current ldm doesnt offer much error feedback to the user if something goes wrong. Porper error feedback should get taken into account for the gui. An often requested feature is to run ldm outside of ltsp environments as standalone fullscreen ssh client, proper initscripts and necessary changes should get implemented. Secure Display Manager (sdm) offers a lot of similar funcionallity ldm has, both projects should get comparison and code/feature merges should get discussed.