Avoid remove-lib error on __del__
Avoid remove-lib error on __del__

With MPI, there was an error on python exit
Exception ignored in: <function KernelSOA.__del__ at 0x7efd4a83bc10>
Traceback (most recent call last):
  File "/nethome/sebil001/parcels/parcels/kernel/kernelsoa.py", line 165, in __del__
  File "/nethome/sebil001/parcels/parcels/kernel/basekernel.py", line 106, in __del__
  File "/nethome/sebil001/parcels/parcels/kernel/basekernel.py", line 206, in remove_lib
  File "/nethome/sebil001/parcels/parcels/kernel/basekernel.py", line 218, in get_kernel_compile_files
AttributeError: 'NoneType' object has no attribute 'Get_rank'

that may confuse users. Putting it in a try/except avoids the error

OceanPARCELS/parcels,OceanPARCELS/parcels