Add ability to show/hide the edges.

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>

Conflicts:
	demos/Graph/index.html
Merge branch 'ShowHideEdges' into gh-pages
Add snap to grid for graph.

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge branch 'SnapToGrid' into gh-pages