polygon-edit: add preview button (no contents)
polygon-edit: dots in a group is now ordered clockwise
polygon-edit: now we can preview the first group of selected region
polygon-edit: now we can preview polygon with box2dweb
polygon-edit: Add CommonData.selectedRegions
polygon-edit: preview all selected regions
polygon-edit: delete existing box2d body when selected regions changed
polygon-edit: higher wall on box2d preview
polygon-edit: multiple select improvement
Merge pull request #4 from nitoyon/preview-box2d

polygon-edit: Preview with box2d