Heatmap based on values instead density about hexgridheatmap

[kronick]

@ktugan Thanks for taking a crack at adding in this functionality. Your code style is good, but you get rid of the gaussian kernel calculation that makes this work as a heatmap: ktugan@7cfa0ec#diff-feb43b13521636d30c38958cccf95c91L166

This creates artifacts like those seen here:

If you add in this kernel with your property value code, make a PR to this repo and I will work it in.

[ktugan]

I implemented my own version of a value based heatmap in a fork without any regards for best practices (since I am not familiar with the javascript ecosystem).

here the diff: ktugan@7cfa0ec