Allow time-dependent rates

[gustavdelius]

I propose a function projectWithTimeDependence() which is like project() but with additional arguments that, similar to effort, are arrays with a time dimension. I think the arguments should be:

• search_vol
• intake_max
• metab
• ext_mort
• maturity
• repro_prop
• resource_rate
• resource_capacity
• interaction
• pred_kernel

Their values should be arrays that are like the arrays stored in the MizerParams object but with an extra first dimension for the time.

The function would simply need to update the rate arrays in the params object during project(), using the new save_callback discussed in #236.

The function should also save the time-dependent arrays in the resulting MizerSim object.

I think this function should be supplied by an extension package, which could also provide convenience functions for setting up the time-dependent arrays, provide examples like global warming, and provide appropriate analysis functions and plots.