The doxygen comments have been fixed and largely expanded: the welcome page is now populated and some general documentation proposed. 

The prototypes of the filters have been fixed (doxygen was complaining) so that we always use std:: when necessary.

The Grid3DObject checkCoordinates has been implemented along the same lines as Grid2DObject. The altitude is still missing though...

The check for POPC++ has been added to the autotools configuration. 

A small improvement to the way the A3DIO plugins handles incoming nodata has been done. A few HACKS have been fixed and removed. Some error messages (in libinterpol2D) have been improved, their printf relpaced by a std::cerr and an extra check (using assert) has been added so that no Td would be computed if Rh<0 (and we would throw an exception).