gdal_priv.h changes

[Frank Warmerdam]

Folks,

I have made a few changes to the GDALDataset class that will require any
updating their source from CVS to to a make clean before rebuilding.

The changes related to the addition of the GDALOpenShared() function which
keeps a registry of open datasets and allows them to be reused by other
parts of an application. This has primarily been done for the virtual
dataset code, to avoid ending up with many open handles to underlying
datasets. Eventually OpenEV will be upgraded to use GDALOpenShared() though
it already tries to do something similar itself.

Best regards,

-- 
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at p...
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and watch the world go round - Rush | Geospatial Programmer for Rent