Option to turn off edge outlines in heatmap segments

[big-o]

Great library! I've been using it to generate some plots with a background that has a different colour at each corner, and becomes more opaque at the centre.

I've noticed that when you set the alpha to < 1, you start to see the edges around each segment. This creates an unwanted "grid" which is either triangular or hexagonal.

Simply setting the edgecolor to "none" in the ax.fill call in heatmapping.heatmap seems to fix it, and produces a lovely smooth effect.

Can we either get this changed, or make it a configurable option to turn off the edge lines?

[marcharper]

So basically you want to be able to pass through arguments to ax.fill ? That seems fine to me.

[big-o]

Pretty much. I'd argue that defaulting edgecolor to 'none' too would be a better choice than the current default behaviour, but that's a matter of opinion and if we can override then it doesn't really matter anyway.