Several visual tweaks to node links to make them overall fit in
better with the look of the node editor:
- Change the link thickness with the zoom level to a certain degree.
- Remove the fuzziness of the node link and its shadow/outline.
- The link outline color can now be made transparent.
- Add circles at the end of dragged links when connecting to sockets.
- Improve the banding of the color interpolation along the link.
- Adjust the spacing of dashes along straight node links.
Reviewed By: Pablo Vazquez, Hans Goudey
Differential Revision: http://developer.blender.org/D15036
9a86255da8