Add hex bin option to WMS

[adam-collins]

Hex bins will operate the same as grid bins, e.g. the current sizing parameter, but include a border if requested, e.g. same as points.

Also include a new parameter to override the default colour ramp.

Something that does the equivalent of "colourRamp=value" where "value" is "colour1,count1,colour2,count2,colour3", colours are RGBA hex, and used as defined here:

• use colour1 when count <= count1
• use colour2 when count <= count2
• use colour3 when count > count2

[adam-collins]

Observations

• Resizable grids scaled to a tile pixel resolution has limitations. Bigger grid cells look better. Zooming out is better (tile zoom not map level zoom).
• I like the polygon edges from the default RenderingHints applied. The appearance varies depending on grid size.
• Refer to the Java code if you need a reference on how to convert a pixel coordinates to polygon coordinates.
• Using the old method of rendering so performance will vary more. It all depends on the use case.
• Stitching tiles together was more trouble than it should have been. I think I found all of the errors, rounding and otherwise. Testing will tell.
• A demo page was useful for playing with the map. Should put together something public.

[adam-collins]

Received a comment about removing that faint border between cells.

[adam-collins]

Any other feedback?

[adam-collins]

Removed the border between cells. This is in test for confirmation. example

There was a buffer applied to adjust for the aliased edges. It looks OK in the given example but if you find another where it is not, please provide a link to the incorrect image.

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