Consolidation with CDI-PIO (develop)

Generally, this is !11 (merged) rebased onto the develop branch.

This is the first develop-based version accepted by the Buildbot of ICON: https://buildbot.dkrz.de/grid?branch=m300488/cdi-pio-2-integration

src/grid.h

@@ -54,7 +54,7 @@ struct gridVirtTable
 #endif
   double (*inqXInc)(grid_t *gridptr);
   double (*inqYInc)(grid_t *gridptr);
-  // return if for both grids, all xval and all yval are equal
+  // return true if for both grids, any xval and all yval differ
   bool (*compareXYFull)(grid_t *gridRef, grid_t *gridTest);
   // return if for both grids, x[0], y[0], x[size-1] and y[size-1] are respectively equal
   bool (*compareXYAO)(grid_t *gridRef, grid_t *gridTest);