.gitignore add Makefile and cscope.out
Release backend resources for vkbd when required

When input thinks the domain is gone, it might as well not keep a vkbd
backend up for that domain (which means an allocated evtchn etc in
libxenbackend).

This used to clog input_server when dm-agent was restarted.
Fix pending segv

mouse_dest can be NULL when entering input_track_mouse_position (it is
actually tested before the switch), for example if the xenstore node is
not created by the guest.
Merge pull request #2 from eric-ch/master

Release vkbd resources, fix SEGV misery, allow dm-agent to be restarted