GeoJSON as input format

[kuuup-at-work]

Hi.

It would be useful if we could input GeoJSON data without extracting coordinates. Styling information can be provided by the properties section so data could be used by staticmaps and other libs interchangeably.

[StephanGeorg]

My suggestion for this: To keep backward compatibility, keep the addFeature methods and add a new addGeoJSON method that then passes the data to the respective method.

[leoalho]

Hi, I got interested in implementing this and created an addGeoJSON method. I have made a pull request for it, #87. Please let me know what you think.