RST - It is not reporting the whole color table

[ilucena]

When the RST driver finds a companion .smp file, it should read it as a Idrisi color table but that code:

http://trac.osgeo.org/gdal/browser/trunk/gdal/frmts/idrisi/IdrisiDataset.cpp#L592

Is preventing it to report the whole color table (256 items) but only up to the maximum pixel value of that image.

That change was introduced on r 10807 to provide a better support for thematic data, category names and color table of each classes because some other driver and some other software got confused with "Why a raster with 10 classes with pixel ids going from 0 to 9 have 256 color items?"

But that restriction is affecting images that are not classified and that is a bug.

[ilucena]

I added code that checks if a image is thematic before applying the color item restriction.