fmbt-editor: support parameter combo -p -P

--preview-only and --no-preview combination launches two fmbt-editors,
the first has only editor, the second only preview.
Feature: Draw circles connected by lines in place of coordinates
Merge Cosmin's iGestureScreen patch
Reverted installing relax2.py to /usr/bin

Relax2 will not become part of fMBT public interface with that
name. It broke RPM packaging, too.