[Carto] Overview diagram

[Tyler Mitchell (OSGeo)]

Hi all, in an effect to set a bit of a baseline for the kinds of  
things we hope to obtain from this project, I drew up this diagram:

http://wiki.osgeo.org/wiki/Image:Carto_engine_v1.png

Note I didn't define anything without the main process box  
"cartographic engine", but rather just wanted to show the types of  
inputs and where they might come from.

It's meant to be extremely general, but I thought it might help to  
get the cards on the table.  I've added it to the wiki page too:
http://wiki.osgeo.org/wiki/OSGeo_Cartographic_Library

Does it make some sense?

Tyler