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

examples/Makefile.am

+SUBDIRS = pio
+
 check_PROGRAMS = \
   cdi_append \
   cdi_copy \