irstv/H2GIS — pull request #241 by ebocher (2014-03-27 20:08:35+00:00)
Title: Ringbuffer function

Add the ST_RingBuffer function.

The signature is :

```mysql
SELECT ST_RingBuffer('POINT(10 10)'::GEOMETRY, 10, 3)

```

returns a multipolygon with 3 rings buffer. The distance between each rings is 10 meters.