Mapserver needs to report detailed capabilties of optional components

[bfraser@…]

In order to speed up the web site debugging process, it would be useful if 
mapserv (and shp2img) would display detailed information regarding the 
components linked in.  In GDAL's case this could be the GDAL version number, 
the raster formats available to it, and simlar OGR details.  If the other 
components have methods for reporting version numbers and capabilties it would 
useful to report that information as well.

 Related suggestions:
   - have template variable so information can be sent in web page
   - have option for XML output format for automated parsing of info
   - have function callable by mapscript