bug in spitter call (MAIN branch)

[har917]

As per #354 - we need to retrofit the model (MAIN branch) to allow for the original intent of spitter to be used in offline studies.

This will need to be different in MAIN compared to older offline branches such as CABLE-POP-TRENDY/BLAZE/NESP2pt9

[har917]

The code changes in #355 can be simply applied in MAIN - but placed in the cbl_init_radiation() MODULE

[har917]

Following discussion in #354 and with NRI staff - will apply the necessary (1-line) bug fix into a dev branch from MAIN and then assess in benchcab/me.org. This will give an assessment of the relative importance of the bug on the biophysics - from which we can infer/estimate impact on the biogeochemistry.