reposition: 'drag' : Option to drag certain elements along with others

[maxkfranz]

Sometimes you want to treat certain nodes as being dragged along with a particular node when it's grabbed. For example, you might want to drag along an entire component when a node within it is dragged.

Usecase : Dragging interaction participants in Factoid along with an interaction

• reposition: 'drag' enables the mode on nodesMatching -- these are the nodes that get dragged with the master nodes
• dragWith: otherNodes specifies the master nodes that are listened to for drag events
  • otherNodes can be a collection, selector, orfunction( node ){ return trueOrFalse; }

// for `reposition: 'drag'`, specify nodes that when dragged cause the matched nodes to move along
// - a function that returns true for nodes to be listened to for drag events
// - a selector that matches the nodes to be listened to for drag events
// - a collection of nodes to be ignored (very good for performance)
dragWith: function( node ){ return false; }