Added optional coordinateConversion method

[tadiraman]

Example usage (for GlobalMercator, see https://gist.github.com/tadiraman/12f850ad5a6bdcdc59fb):

var mercator = new GlobalMercator();
var converter = geojson2svg(viewportSize,
   {coordinateConversion: mercator.LatLonToMeters});

This can be used to generate SVG with correct projection to match web maps.

[gagan-bansal]

Yes reprojecting geojson to Web Mercator or other desired projection is very fundamental requirement. In my example's javascript code I reproject geojson from WGS 84 to Web Mercator projection using reproject. i.e. based on proj4js projection library.

 // covert wgs84 data to Web Mercator projection
var geojson = reproject.reproject(
geojson,'EPSG:4326','EPSG:3857',proj4.defs);

My idea is to keep the geojson2svg as modular as possible, do not want to make it as library. May be collection of such tools (GlobalMercator, reproject etc) combined together with geojson2svg can make a library.
That is why I didn't include reprojection in geojson2svg module.

Please feel free to discuss further and thanks for taking interest in geojson2svg.