Implement DOC, DOR, POC, POR

[nanophyto]

This will replace the detritus component with explicit particulate and dissolved organic matter pools.

$$ \begin{equation} \partial_t \mathrm{DOC} = \sum_j M_j^{\mathrm{DOM}} + g^{\mathrm{DOC}} - R_{\mathrm{DOC}} \end{equation} $$

$$ \begin{equation} \partial_t \mathrm{DOR} = \sum_j M_j^{\mathrm{DOM}} Q_j^{{\mathrm{R}}} + g^{\mathrm{DOR}} - R_{\mathrm{DOR}} \end{equation} $$

$$ \partial_t \mathrm{POC} = \sum_j M_j^{\mathrm{POM}} + g^{\mathrm{POC}} - \sum_j U_j^{\mathrm{POC}} - R_{\mathrm{POC}} $$

$$ \partial_t \mathrm{POR} = \sum_j M_j^{\mathrm{POM}} Q_j^{\mathrm{R}} + g^{\mathrm{POR}} - \sum_j U_j^{\mathrm{POR}} - R_{\mathrm{POR}} $$

This will require:

#21 and #18

Here R=any nutrient and could be used to represent N, P, or Fe.