The nodata handling strategy was not thoroughly implemented: aritmetic operators were not compliant. In order to fix it, a property now records how to handle nodata for each object. A setter method is available. All operations now properly handle it.

The Grid2D and Grid3D objects now have a (x,y) and (x,y,z) method for direct access to their gridded values. This should make it easier to switch a Grid object with an Array in a piece of code.

With the latest changes in CMakeLists, the examples could not be built anymore. This has been fixed in the examples Makefile (but the io.ini plugin path stil has to be fixed).