Parallel build broken on ubuntu 18.04

Created by: acrovato

CUPyDO can be built on ubuntu 18.04, but will hang upon execution of any test case when building interpolation matrices.

Preliminary tests suggest that the issue is due to mpi, as the code seems to hang at cupydo/interpolator.py:632

self.mpiComm.Send(localSolidInterface_array_X, dest=jProc, tag=1)

Fortunatelly, CUPyDO currently runs fine on debian, and should be supported on ubuntu 16.04 (I am currently testing). I will further investigate.