moveoff: support -mode always, fixes from testing

moveoff.comp
  rename is-on pin to power-on and clear offsets on removal
  remove redundant calls to offset_removed()
  issue warning message in any state
  remove unused vars
  revise some var names for clarity
  work on man page

moveoff_gui
  connect mv.power-on to motion.motion-enabled
  add -mode onpause|always option
  show status in white if motion.motion-enabled false (always mode)
  if timing out autoresume, check if other actor resumed
  show mode in window title
  revise some var names for clarity
  disallow window delete
  is_connected() return signame too
  connect is-paused to existing sig if already connected

moveoff_demo[45]a.[ini|txt]
   demo configs for -mode always

hookup_moveoff.tcl
   if [AXIS_n]OFFSET_MAXIMUM_VELOCITY (and like items) do not
   exist, try [AXIS_n]MAXIMUM_VELCITY (and like items)
   else use component defaults
   honor ini entry for BACKTRACK_ENABLE

moveoff.txt
   update for -mode option

Signed-off-by: Dewey Garrett <dgarrett@panix.com>
moveoff_gui: new manpage

and remove redundant text from the script
also: brief manpage for sim_pin

Signed-off-by: Dewey Garrett <dgarrett@panix.com>