Add control option for linearization of WFS GML output

Here's a new customer feature which I would like to offer for inclusion in deegree 3.4: It allows to activate/configure linearization of geometries returned by the WFS.

Motivation:

There are two reasons why you may not want your WFS to return non-linear GML geometries:

* There's no encoding for non-linear GML geometries in GML version 2
* Currently available WFS clients (e.g. QGIS, uDig, ...) cannot cope with them

Usage:

Option GeometryLinearization (in section GMLFormat) will ensure that GML responses will only contain linear geometries. Curves with non-linear segments and surfaces with non-linear boundary segments will be converted before they are encoded to GML. Example:

```xml
...
<GeometryLinearization>
  <Accuracy>0.1</Accuracy>
</GeometryLinearization>
...
```

GeometryLinearization has a single mandatory option Accuracy. It defines the numerical accuracy of the linear approximation in units of the coordinate reference system used by the feature store. If the coordinate
reference system is based on meters, a value of 0.1 will ensure that the maximum error between the original and the linearized geometry does not exceed 10 centimeters.