WMS context misses ogc namespace declaration

[bartvde@…]

The WMS Context saving code currently misses the ogc namespace definition:

msIO_fprintf( stream, " xmlns:ogc=\"http://www.opengis.net/ogc\"");

Should be a minor fix, but otherwise a lot of SLD's (anything with a filter
basically) generated by Mapscript won't be valid ....

[bartvde@…]

"but otherwise a lot of SLD's" should be "but otherwise a lot of WMC's"  ....

[tomkralidis]

Bart: now in r6073