* Some tests do fail (reflecting problems with events for restarts in
  ICON, affecting the atm_amip experiment).

As a first step, generate tests from the example code in
ac66aeae .

* Needed to handle arrays of datetime objects.

* mtime_juliandelta:
  [mtime_juliandelta]  public fortran interface for julian delta objects.

* The actual pointer association is not modified and this way the actual
  intent can be specified.

* The tab character is not allowed by the Fortran standard.

[divideTwoDatetimeDiffs] bugfixes in src/libmtime.f90, include/mtime_timedelta.h and src/mtime_timedelta.c