Update the carbon chemistry code to using mocsy

[JorgSchwinger]

Update the carbon chemistry code to using mocsy (www.geosci-model-dev.net/8/485/2015/). Details remain to be discussed.

[jmaerz]

Hi @JorgSchwinger , just stumbled over this issue. Is this still on the todo list or did it actually became obsolete with #446 and can be closed?

[JorgSchwinger]

I think this is only loosely related to #446 - it's a question of whether we want to switch to a standardized package or do our own thing. I wouldn't see this as a priority right now given that our carbon chemistry is working fine, and enough other things to do...