per-year parameters for projections

[lentinj]

Having a per-year parameter for projections is an obvious thing to want to do, but quite tricky currently, with constructs like:-

hr_vec <- g3_formula(
  g3_param_table('project_hr',
    expand.grid(cur_year = seq(end_year + 1L, end_year + py)),
    ifmissing = 0),
  py = num_project_years)

This isn't obviously solved, because "project_years" is itself a parameter, and so can't be used to redefine how many parameters a model has.

Some variously-baked ideas:

• Force models to use a hard-coded project_years (which is unlikely to be popular.
• Add a "max_project_years" option to g3a_time which is hard-coded like the project_years, that a g3_parameterized(by_year = "project" )) could use?
• A data update mechanism that checks dimensions match before allowing update. Use this to allow modification of start_year/end_year/project_years.
• Encourage use of g3_timeareadata for cases like the above.
• Do we actually want a fishingyear option, rather than calendar year?