Static images: Allow styling each path differently

[samuel-git]

Each path was rendered with each path style, drawing over the correctly styled path. Now each path gets only rendered once with the specific path style.

This is now possible:

With this URL:

http://localhost:8080/styles/basic-preview/static/auto/750x250@2x.jpg?path=stroke:yellow|width:2|fill:green|5.9,45.8|5.9,47.8|10.5,47.8|10.5,45.8|5.9,45.8&path=stroke:blue|width:3|fill:red|4.9,44.8|4.9,46.8|9.5,46.8|9.5,44.8|4.9,44.8

[acalcutt]

I finally got a chance to test this and it seemed to work good. I tested with you example and examples from the previous PR and they all still seemed to work as expected.

thanks for submitting this.