Update group.class.js

added managing of  originX/Y to group.
Update group.class.js
Update group.js
Update canvas_grouping.mixin.js

Removed forced originX/Y from dynamically created groups
Update group.class.js
Update group.js
Update group.js
Merge pull request #1765 from asturur/fix-for-group-position

Fix position of group for originx/y different from center.