* This way it becomes easy to inject program starters for all parts of the
  tests, which makes working in cross-compilation setups much easier.

* And add corresponding check to test suite.

* Since write, mmap and a number of other functions are not part of
  ISO C (i.e. strictly conforming programs must not use those), we need
  to ensure the build environment provides POSIX conformance.
* This mostly prevents unrelated bug reports later on.
* From POSIX 2008, CDI unconditionally only uses getline and has a
  work-around in case that is missing.

* This way re-ordering of GRIB records does not change checksums.

Removed obsolete CDI grid functions gridXXXXpole(), gridXXXYpole(), gridXXXAngle() and gridIsRotated().

* Also add corresponding switch to test code.

* This version is still sub-optimal and transfers more data amongst the
  I/O server processes than strictly necessary.

* Having a configuration object will allow future extensions without
  a change of interface to cdiPioInit.
* Also move code to translate I/O mode string vs. integer into library.