[SLD]: Support Property Names when parsing some sld parameters

[assefa]

Currently we support a literal value for some parameters: <se:Rotation>60</se:Rotation>

We should support also the use of propertyname syntax and use attribute binding:

<se:Rotation><ogc:PropertyName>angle</ogc:PropertyName></se:Rotation> : would end up being translated into:

LABEL

angle [angle]

[assefa]

committed support for Rotation (r9248).

what other parameters do we need to support?

For text symbolizer:

• <se:SvgParameter name="fill">: to be used with the color parameter in the label object

• <se:SvgParameter name="stroke">: to be used with the outlinecolor parameter in the label object

• <se:SvgParameter name="font-size">12</se:SvgParameter>: to be used with the size parameter in the label object

• font ??: this is a bit trick since the font name is currently extracted from 3 parameters in the sld: font-family, font-style, font-weight

For point symbolizer:

• <se:Size>: to be used with the size parameter in the style object

• <se:Rotation>: to be used with the angle parameter in the style object

• <se:SvgParameter name="fill">: to be used with the color parameter in the style object

• <se:SvgParameter name="stroke">: to be used with the outlinecolor parameter in the style object