Improvements to demo scripts. Alias -coe for -connect_or_exit.  Fix HAVE_V4L2. Warn no Xvfb, Xdummy, or Xvnc. Xinerama screens.

x11vnc: exit(1) for -connect_or_exit failure, quiet query mode for grab_state, pointer_pos, etc. ipv6 support. STUNNEL_LISTEN for particular interface. -input_eagerly in addition to -allinput.  quiet Xinerama message.

x11vnc: small tweaks to Xdummy, rx11vnc*.  Apply SMALL_FOOTPRINT to -appshare text.  Copyright year change.