Use t_max and t_save even when effort array is supplied to project()

[gustavdelius]

An interesting point came up in an example by @juliablanchard which had an effort array with an NA in the effort for the final year.

Currently the t_max argument in project() is ignored when the user supplies an effort array and the final time is taken from the effort array. Instead the final time in the effort array is used to determine the end time of the simulation. This was done originally for backwards compatibility with mizer 0.3. This has the drawback that the user needs to make up values for the effort at the final time, even though that effort will not actually be used during the simulations.

I propose that we change that and use the t_max value when it is supplied to determine how long the simulation should run, even when an effort array is provided. Then for example someone who has effort values until and including 2018 can run the simulation until 2019 by setting t_max = 2019 instead of making up a value for 2019.

Similarly I propose that the t_save argument is used to determine at which times the simulation values are saved, even when an effort array is provided. When t_save is not supplied, we will continue to save at the times specified in the effort array.

So the only argument that will continue to be ignored when an effort array is supplied is t_start.