Feature/geotiff reader improvements

Fixed one orientation, it is a lot of work to fix them all. Also optimized LZW decompression.
Well, the Proj4 string is something that represents a CRS. A CRS can live without a proj4 string though. The proj4 string is one way to represent or create a CRS; another way would be with Well Known Text. So there is some reason for separating out the responsibility of managing the details of how proj4 strings work from the CRS object. But I think this is fine for now. I might end up doing some refactoring to it as part of the port completion, or maybe later as we introduce WKT as a format for reading\writing CRS's.