* Also sizeof (char) == 1 by C language definition.

* Otherwise snprintf might truncate the output.

* Otherwise, gcc assumes large numerical values of the time stamp
  components might lead to truncation of unitstr_.

* This way the compiler can first use isText and isNumber to decide on the path.

* Using a pointer after realloc is UB.

* Additional pointers complicate alias analysis.

* levels1 and levels2 already have a sentinel value.

* The previous version did not properly use libtool.

* The ternary above already ensures that datatype only takes values
  from the interval [1,32].

* It is possible to build netcdf 4.x without HDF5 but with MPI
  parallelization support.