* This prepares for derived resource class packing, i.e. extends the set of
  operations that can be applied to in fact different objects.

* The changes in this commit delay calling of inq[XY](Vals|Bounds)Ptr
  until the absolute last time possible in the affected functions.

* This way the availability of mask, [xy]-{bounds|values} etc. can be
  queried without adding a method each time.

* This implies NetCDF data mode is only entered once, unless missing values
  are written later.

* Otherwise the compiler is not allowed to fold the storage of stdname,
  longname and units into one.

* Localize independent uses of variable timevalue in the respective blocks.
* Merge calls to cdf_get_vara_double for time bounds.
* Move invariant data to text segment.

* This can next be used to create the storage for NetCDF streams.

* The entries of the direct table are smaller than the Iliffe vector,
  even for 4-byte pointers.

* delete_refcount_string contains just this test and is likely to be
  inlined.

* taxis.c contains calls to fprintf.