select() API function toggles point, rather than selecting/unselecting it

[nbdavies]

• C3 version: 0.4.15
• D3 version: 3.5.17
• Browser: Chrome 60
• OS: Mac OSX 10.11.6

jsfiddle: https://jsfiddle.net/7d8n838t/31/

The intended result here is that if you hover over a line point, it and the associated bar will get the selected effect. Same should happen if you hover over the bar.

However, the current problem is that if your cursor travels from the point to the associated bar, or vice versa, there is a good chance that the select effect will not be re-triggered for the line point.

I haven't spotted the issue in the source code, but it seems like the circle's selectedness is being toggled rather than set to the appropriate boolean value.