[mapguide-internals] RFC60 for vote please

[UV]

Please have a look at the patch submitted for RFC60.

This is straightforward code so lets please commit it finally.
* Collection of color strings in VectorScale.
* Pruning the list in the renderer service. (this is were those strings 
can be parsed differently)
* Using the list in AGGImageIo.
The rest is comments and boilerplate code passing on parameters.
Any additional functionality can be easily added later.

I spent months now evaluating this patch as I had to be sure that the 
problems were not from my code.
So I am sure now that any problems I found are in any release build as 
of 2.1 where incomplete tiles can be generated.
This, as we know now, has been called a feature and is caused by the 
exception handling in the stylization code
which can be caused by resource limitations of the server.
But this is not part of RFC60.

So as there were no comments for quite some weeks this should be ready 
to go.
Its difficult to work on different patches without a repository.