work on svg implementation of scg

- added node/edges creation;
- simple force layout;
- not finished contours
work on scg-contour
component interface implementation

implementation of component interface for sc-web
first version of scg-component for sc-web
fixed scg-viewer for firefox
fix viewer expand by height; improve some visual parts
tune layout
done issue #1 (sc.g-nodes alphabet support)
done issue #2 (support of sc.g-edges alphabet)
done issue #6 (fixed bug with nodes draw in firefox)
work on issue #3 (base edit commands)
work on issue #3 (arc points support, work on text identifiers)
add missed files
done isue #3 (base edit commands)
done issue #9 (fixed construction from json)
merge svg branch