Experimental SDE Raster support

[Howard Butler]

Folks,

I would like to comment out the experimental SDE raster support that 
we have in mapsde.c for the time being.  As far as I know, I'm the 
only one to ever get it to work, it hasn't kept up with the 
connection pooling stuff we did, and its utility is quite limited in 
comparison to regular gdal-based raster support (projections, 
resampling, etc).

The code would make a nice prototype for implementing SDE raster 
support in GDAL, just as the mapsde.c code was a good prototype for 
vector support in OGR.  I propose that we keep it around, but switch 
it off for now unless someone wants to step in and get it up to snuff 
with the current things going on (layer virtualization, connection 
pooling, projections, resampling, etc).

What do people think?

Howard