Allow individual Line chart point colors

[AndiDog]

Is your feature request related to a problem? Please describe.

Only the series is passed to pointColor if that property is provided as function

nivo/packages/line/src/hooks.js

Lines 48 to 49 in c361e9b

	point.color = getPointColor(serie)
	point.borderColor = getPointBorderColor(point)

With that, it's impossible to know which point (x, y, ...) it is, in order to give it the desired color. For example, if I want to do point.y > 10 ? 'red' : 'black', that's not possible with the function's current parameter.

Describe the solution you'd like

I guess this should mostly do it:

-point.color = getPointColor(serie)
+point.color = getPointColor(point)

It's even already the case for borderColor.

I also suggest to assign point.data first so that the callback can use datum.data, xFormatted and yFormatted which include the original values. Else, only the rendered X and Y coordinates are available which may not be of much help.