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

          serverCert param, debugging printout, user dialogs, catch
          socket exceptions, autodetect x11vnc for GET=1.
x11vnc: misc/scripts: desktop.cgi, inet6to4, panner.pl.
          X11VNC_HTTPS_DOWNLOAD_WAIT_TIME, -unixpw %xxx documented, and
          can run user cmd in UNIXPW_CMD. FD_XDMCP_IF for create script,
          autodetect dm on udp6 only.  Queries: pointer_x, pointer_y,
          pointer_same, pointer_root.  Switch on -xkd if keysyms per key >
          4 in all cases.  daemon mode improvements for connect_switch,
          inet6to4, ultravnc_repeater.pl.  Dynamic change of -clip do
          not create new fb if WxH is unchanged.

ultravnc_repeater.pl scripts, find_display try FD_XDM on failure,
-quiet and -storepasswd changes, better port 113 testing.