Simulation Ratio preference
Auto-shape feature, polygon-group feature

I added auto-shape feature and polygon-group stub. From now in image
frame you can add polygon group and in them you can add polygons. Also
in image frame menu appear a auto-feature option which brings you
appropiete form with options to set. I didn't know what values should be
for hull and alpha tolerence so you need to set them on your own (in
designer and code behind) and change a little. When you have selected
polygon group in image viewer all polygons in that group appear. When
you select specific polygon you also see all polygons, but selected is
in another color. Both json (suf and export) was changed to reflect this
changes. In preferences you have option for simulation ratio and
selected polygon color.
Polygon Group Stub Color, open document bug

Added polygon group stub color to preferences, also fixed bug with
opening document on launch (asking about save document, where we don't
have any)
poly group and poly stubs selection fix