Color extensions

[ebocher]

• Add RGBColor extension with the encoding : rgb(255,0,0)

• Add HexaColor extension. Notation is notation is a ‘#’ immediately followed by either three or six hexadecimal characters.

• Add WellKnownNameColor extension with a list of color names as proposed by X11 : https://en.wikipedia.org/wiki/X11_color_names

[ebocher]

The feature2 style supports now the rgb, hexa and wellknown name columns.
The color elements is encoded as

<Feature2DStyle>
  <Name>Unnamed Style</Name>
  <Rule>
    <Name>Default Rule</Name>
    <LineSymbolizer>
      <Name>LineSymbolizer with WellknownNameColor</Name>
      <Uom>PX</Uom>
      <Level>0</Level>
      <PenStroke>
        <SolidFill>
          <Color>orange</Color>
        </SolidFill>
        <Width>0.25</Width>
        <LineCap>BUTT</LineCap>
        <LineJoin>MITRE</LineJoin>
      </PenStroke>
    </LineSymbolizer>
    <LineSymbolizer>
      <Name>LineSymbolizer with  WellknownNameColor expression</Name>
      <Uom>PX</Uom>
      <Level>0</Level>
      <PenStroke>
        <SolidFill>
          <Color>expression(orange)</Color>
        </SolidFill>
        <Width>0.25</Width>
        <LineCap>BUTT</LineCap>
        <LineJoin>MITRE</LineJoin>
      </PenStroke>
    </LineSymbolizer>
    <LineSymbolizer>
      <Name>LineSymbolizer with RGBColor</Name>
      <Uom>PX</Uom>
      <Level>0</Level>
      <PenStroke>
        <SolidFill>
          <Color>rgb(0,0,0)</Color>
        </SolidFill>
        <Width>0.25</Width>
        <LineCap>BUTT</LineCap>
        <LineJoin>MITRE</LineJoin>
      </PenStroke>
    </LineSymbolizer>
    <LineSymbolizer>
      <Name>LineSymbolizer with  RGBColor expression</Name>
      <Uom>PX</Uom>
      <Level>0</Level>
      <PenStroke>
        <SolidFill>
          <Color>rgb(expression(22),expression(15),expression(120))</Color>
        </SolidFill>
        <Width>0.25</Width>
        <LineCap>BUTT</LineCap>
        <LineJoin>MITRE</LineJoin>
      </PenStroke>
    </LineSymbolizer>
    <LineSymbolizer>
      <Name>LineSymbolizer with HexaColor</Name>
      <Uom>PX</Uom>
      <Level>0</Level>
      <PenStroke>
        <SolidFill>
          <Color>#000000</Color>
        </SolidFill>
        <Width>0.25</Width>
        <LineCap>BUTT</LineCap>
        <LineJoin>MITRE</LineJoin>
      </PenStroke>
    </LineSymbolizer>
    <LineSymbolizer>
      <Name>LineSymbolizer with HexaColor expression</Name>
      <Uom>PX</Uom>
      <Level>0</Level>
      <PenStroke>
        <SolidFill>
          <Color>expression(#000000)</Color>
        </SolidFill>
        <Width>0.25</Width>
        <LineCap>BUTT</LineCap>
        <LineJoin>MITRE</LineJoin>
      </PenStroke>
    </LineSymbolizer>
  </Rule>
</Feature2DStyle>