ISIS2 Improvements

[warmerdam]

Hi,

i have a patch for gdal 1.7.3 to improve isis2 driver. The patch had

• writing functionality for QUBE object
• grab null value
• improve the type reading
• can read qube with back plane, side plane and bottom plane
• can read a file with label detached or attached.

and i have modify nasakeyword handler to reduce sensibility of parser to little error on comment. (Like if we have char after end comment.)

but i have rewrite/move a lot of lines... I use this patch for a research project from one year ago. I work on hyperspectral data with OTB library.

I think is it possible to easily merge pdsdataset.cpp and isis2dataset.cpp pdsdataset work on IMAGE tag and isis2 on QUBE tag but it is the same workflow for all object (QUBE, IMAGE or SPECTRAL_QUBE)

Warning for writing no geographical information are writing now, and create_copy is not implemented.

Ludovic.

[warmerdam]

ISIS2 improvements from Ludovic.