New projections worldmap: Mercator and Miller

[Indigo744]

Implements #37 as requested. Add also a Miller projection :)

[neveldo]

Great work, well done !!

Was it not too hard to find resources for dealing with these projections ?

Maybe later we could provide a tutorial to create maps with miller or mecator projections, but your examples is already clear enough for understanding.

FYI, I'm currently working a map more accurate world map with equirectangular projection.

[Indigo744]

It was quite difficult, yes. For instance, there are a lot of resource for Mercator projection, but using different algorithm and leading to different results, without any explanation from their authors...

I was glad to find finally a good resource that explains how to convert coordinate, and project into the map.

Also, I wanted to add initially the Robinson projection, but after too much failed attempt I decided to gave up :-/ maybe I will retry later.

The nice thing here is that the getCoords() function is common to all map. Only the projectLatitude and projectLongitude algorithm are needed.

Hence, we could use an existing library like proj4js to convert between coordinate system.

[neveldo]

Thank you for the explanation, the Robinson projection seems to be more complexe indeed. I agree with you regarding proj4js,maybe it could be a good idea to make some of the JS maps based on proj4js algorithms.