First vectorised rules -- only time coords for now.
Fixed problem with new test in tests/integration/test_pp.
reinstated scalar only _convert_scalar_time_coords() in pp_rules
reverted some test changes that are unnecessary now that alternative code path is not used
tidy up to test__convert_time_coords.py
removed unnecesary array copies
readability
more use of np.asarray and other tidying
testing
additional tests
one more test
pep8 fixes
review action - docstring
review action - test names
review action - comments
review action - docstring
review action - docstring
review action - test names
review action - readability
review action - lbtim ib=2 issue