polygon gamma suggestions for simple, choropleth, category, and density default settings

[makella]

@andrewxhill please review

The changes proposed in this pull request are:

• to add polygon-gamma: 0.2 to simple, choropleth, category, and density polygons
• for each type of polygon map, the line-width has been set to 0
• in addition, I've adjusted the default size of the hexbins from 15 to 5

Explanation and Examples:

By default, polygon-gamma (polygon-antialiasing) is set to 1. If someone is designing a map and removes the outline, there is a noticeable gap in between each polygon. This is especially true with choropleth and category maps that vary in color over a variety of shapes and sizes. Here are two examples of this effect:

One solution is to modify the line-color of each polygon fill to get a smooth appearance but this can be tedious especially when there are a large number of classes/categories.

A default solution is to adjust the polygon-gamma setting to 0.2. In doing so, the antialiasing is minimized and each polygon appears to have an outline that is a shade of its fill color and makes for an overall smoother looking map:

Density Now:

Proposed (with polygon-gamma and default size of 5):

[andrewxhill]

lgtm!
we'll need someone to test this.
also, i'm not sure the behavior of 'type' and what will happen with the new type, 'gamma'
let's see!

@saleiva can someone spare a few minutes to try this out? i know it isn't the future :) buuuut

[Cartofante]

Can one of the admins verify this patch?

[makella]

After further review, for the new editor, let's not use plygon-gamma instead, we'll have a modified proposal for each map type's cartocss.

cc: @andrewxhill

[xavijam]

Do you feel we could close this PR due to new builder changes?

[makella]

yes, that sounds OK. @xavijam the only thing i would want to be sure of is that we get default styling for polygons (simple, choropleth, etc.) with some specific specs that i have to produce the best looking map while taking the polygon-gamma into account.

[xavijam]

There is no default styling for polygons or lines, they take the same simple style as points, for the moment.

[makella]

totally

i'm working on all that this week!

reference:
CartoDB/camshaft#86
#8163

[xavijam]

Closing this one then 💋

[xavijam]

Not deleting the branch by the way, just in case.