[Tilecache] Possible refactor of TileCache

[Christopher Schmidt]

So, something that bugs me about TileCache is that it's got all the
layer classes in one file, rather than being something that's easy to
'drop in' a single Python file into a directory to add a new layer
class.

I think I have the tools to fix this now -- I've done some work on this
method of operation for another project -- and I think that I'd like to
go ahead and perform this refactoring. 

I'll probably do it in a branch, and then share the results and the
changes that it means on the configuration side.

If I make this refactoring, it would probably lead to a TileCache 2.0 --
same features, but post-refactoring. 

This is just a heads up that this may be something I do some hacking on,
so if you have outstanding TileCache patches, you should get them in now
:)

Regards,
-- 
Christopher Schmidt
MetaCarta