pyngcgui,gremlin_view apps and gladevcp widgets

Python implementation of ngcgui functionality -- works with existing
ngcgui-compatible subroutines.  File selector in gui gives improved
hints for compatibility.  A numeric popup keyboard is available for
use with touchscreens.  Included:
  pyngcgui -- standalone application
  PyNgcGui -- gladevcp widget

Also:
  gremlin_view    -- standalone application for gremlin with common buttons
  HAL_GremlinPlus -- gladevcp widget

The gladevcp widgets can be embedded in guis like gscreen, touchy, gmoccapy

Example simulator ini files are provided for gscreen, touchy, gmoccapy
to show how to EMBED:

  configs/sim/ngcgui/pyngcgui_gscreen.ini
  configs/sim/ngcgui/pyngcgui_gscreen_popupkeyboard.ini

  configs/sim/ngcgui/pyngcgui_touchy.ini
  configs/sim/ngcgui/pyngcgui_touchy_lathe.ini

  configs/sim/ngcgui/pyngcgui_axis.ini

  configs/sim/gmoccapy/pyngcgui_gmoccapy.ini
  configs/sim/gmoccapy/pyngcgui_gmoccapy_with_popupkeyboard.ini
Make home-state a pin, to enable homing trickery