georaster - several improvements and fixes

[ilucena]

This ticket documents several changes on the driver code:

• Change char* to CPLString

UNICODE support.

• Change loading order on CreateCopy

Improve loading performance

• Fix “cannot update an empty GeoRaster”

Georaster without XML metadata could not be updated before

• Implements the Pyramid delete procedure

Using “gdaladdo -clean” is now working.

• Reduce te number of database round trips for 4 to 1 when openning GeoRaster

The first PL/SQL call brings up all that is need for image identification

• Cache when reading and writing multi-band blocks

Improves loading and reading performance

• Query all the Pyramid level at the same time in just one statement for reading or writing

That improves the display in client application

• Implements its own Pyramid builder. It only works if GEOR_INTERNAL_PYR is set TRUE

That is still under development and tests. Not to be announced yet.

[ilucena]

Committed revision 18843.