add id or class attribute to layer

[TomBor]

Ideas

• being able to style a map outside of bertin.js with a simple style sheet in css
• apply the same style to several maps generated with bertin.js
• reduce bertin.js to its logical part or in other word dissociate styling from things related to data

How

• improve structure of the generated svg :
  • each layer must be in a level 1 group and must have an id attribute
  • element inside a layer could have a class attribute (.bubble for bubbles layer...)

[jeandav]

Hello. I am facing this issue as well. Did you manage to find a way around it?