[mapguide-internals] rfc60 ready for review

[UV]

In the sandbox on
    http://svn.osgeo.org/mapguide/sandbox/rfc60/MgDev
you can find a feature branch which is ready to be merged with trunk.
This codetree includes code to deal with new stylization and lookup of 
symboldefinitions in addition to the color lookup in the previous 
stylization.

*in MappingUtil (ExtractColors, FindColorInSymDefHelper)
    strings are collected from the xml definition of the scaleRanges 
which are describing stylization colors.
*in ServerRenderingService (RenderMapInternal:777, ParseColorStrings)
    after the Stylization the found strings are converted into colors 
and passed on to the AGGRenderer
*in AGGImageIo (ImageCopyForcePaletteGD)
    a provided colorpalette is used to optimize the colorquantization 
algorithm for the tile

this code is only executed for PNG8 and GIF tiles.

I further added comments for some existing methods and did some method 
extraction while trying to understand the code.

The interesting question is now if the colors found in the new 
stylization can overlap tile boundaries in a visible way and therefore 
need to be included into the color quantization optimization?

In our map the long edges of the ocean areas with slightly different 
colors where the only ones we could spot,
whereas a slight color change of a line crossing a tile boundary is 
quite hard to spot.


Other than that, this feature is a MUST for everyone using colormapped 
tiles as otherwise such map simply looks ugly .