libtiff overviews fix

Right after the Graphics Libs 3.1, a serious problem with libtiff was fixed. So here’s Graphics Libs 3.1.1. Basically, generating overviews (gdaladdo) was nearly impossible – strip and block errors and crashes. It’s a couple different problems. The StripByteCounts errors and most block errors are fixed.

Another problem (the crashes) is with LZW compressed TIFFs, this isn’t fixed yet. There is a workaround: run gdaladdo on an uncompressed copy, then recompress that with geotifcp (not gdal_translate!), now all the overviews are compressed.