Merge branch 'cleanup/pastix_integration' into 'master'

include/spm.h

include/spm_datatypes.h

src/drivers/laplacian.c

src/drivers/laplacian.h

src/spm_drivers.h

src/spm_read_driver.c

tests/spm_convert_tests.c

tests/spm_dof_expand_tests.c

tests/spm_dof_matvec_tests.c

tests/spm_dof_norm_tests.c

tests/spm_matvec_tests.c

tests/spm_norm_tests.c