Bugs in computation of node positions

[Schichael]

Hello,
the computation of the positions of nodes has bugs. These bugs become visible when you use nodes with different dimensions.
The bug in horizontal direction (the nodes should not be overlapping):

In vertical direction (again, the nodes should not be overlapping):

The issue for the horizontal position lies in the sep() function in dagre/lib/position/bk.js
Here, the half widths of both nodes are added. But the full width of the first node should be used.

The issue for the vertical position lies in the positionY() function in dagre/lib/position/index.js.

[jingmiaohe]

absolutely agree with you