Graph

###Implementation In order to account for how D3 handles edge objects in the force layout (which points to the indexes in the node array of the source and target), the additional variable idx keeps track of a node's "real" location in the array, as if no nodes were deleted at all. ####Note on D3 D3 itself handles the data displayed to links depending on their location and order within the svg element. Therefore it's necessary to treat the line section of the svg element as a stack, where the highest element in the html is the bottom of the stack and the lowest is the top.