ST_MakeGrid and ST_MakeGridPoints

With this PR, we add  the following create functions:

 * `ST_MakeGrid` replaces the `ST_CreateGrid` function
 * `ST_MakeGridPoints` replaces the  `ST_CreatePointsGrid` function

The signatures are

```mysql
ST_MakeGrid('tableName', deltax, deltay);
ST_MakeGrid((select the_geom from aSpatialTable), deltax, deltay);
```

Note:

1. The user cannot set an angle to rotate the grid because we consider that this job can be solved with a post SQL process.
2. The user cannot use a polygon mask to create the points only in a polygon. This operation will be done in the future using a specific function.

In order to simplify SQL spatial uses, new SFSUtilities have been added: 

* `getGeometryFields(ResultSet resultSet)`
* `hasGeometryField(ResultSet resultSet)`
* `getResultSetEnvelope(ResultSet resultSet)`
* `getResultSetEnvelope(ResultSet resultSet, String fieldName)`

See #41.