/*!
\defgroup buffer buffer: calculate buffer of a geometry
\par Source description:
- OGC: Returns a geometric object that represents all Points whose distance
from this geometric object is less than or equal to distance. Calculations are in the spatial reference system of
this geometric object. Because of the limitations of linear interpolation, there will often be some relatively
small error in this distance, but it should be near the resolution of the coordinates used
\see http://en.wikipedia.org/wiki/Buffer_(GIS)
*/