Extend the model with an event table

[clnsmth]

There is considerable variation in sampling events across ecocomDP datasets.

We don't yet have a good way to capture this variance in the model and are resorting to hacks that complicate interpretation and use.

A solution maybe the addition of another ecocomDP table to capture salient bits of information about sampling events. @sokole do you have any ideas for what an event table should look like or alternative ways of capturing this information in the model?