geometry: IsSolid() and Move() methods, segment overlap detection, some improvements in SHAPE_LINE_CHAIN class.

- fixed walkaround bug causing unwanted overlap/clearance violation when the first segment of trace being laid intersects the obstacle's hull at the same point twice (ie. goes in, turns around and goes out).
- fixed placer bug not splitting the start segment after toggling via placement or changing trace width

Remove a minor compil warning in shape_collisions.cpp

template<> -> template <>
Some more reformatting according to uncrustify results.