Improve renderSpeciesPhenophases() handling of radius

[dhornbein]

The initial phenophases can appear too close to the center of the pClock. Currently the phenophase's index is multiplied by the initial radius.

js/pclock.renderer.js:96

for( var phenophase in phenophases ) {
      var start = phenophases[phenophase].start,
        end = phenophases[phenophase].end;
      if( start && end ){
        var phenophaseElement = this.paper.path().attr({
          "stroke": "#" + sp.color,
          "stroke-linecap": "round",
          "stroke-width": Math.max( this.options.strokeWidth * ( zoom * 0.075 * speciesIndex ), 3 )
        }).attr({
          arc: [ center.x, center.y, r * speciesIndex, start, end ]
        });
        phenophaseElement.node.setAttribute("class", slug );
        sp.registerPhenophaseElement( phenophaseElement );
      }
    }

There needs to be some way to set the radius "dead zone" in the middle and raise the increment between each phenophase by the stroke width rather than initial radius.

[thiagodemellobueno]

Remember that the amount of data on the chart, and current zoom level can fix all this... if the center gets crammed, but we can see more data when zoomed out, whats the harm?
It's not about looking good in a certain spot, as much as allowing access to the data in a variety of unpredictable circumstances.