* Now offering `pe` and `pejit` that can make an argument constant. This will cache the argument and all functions that only depend on that argument as constants. These will be treated as compile time constants when using `pejit`
* This can speed up code noticeably but doesn't always. On `test_ODE` there was a speed gain of ~50x, but on `test_PDE` there was no noticeable difference.
* `constant_arg_nums` has been added to `LS`, `LsClass`, `NLLS`, and `NllsClass`. If this argument is used, then it will utilize `pejit` rather than `jit`.
* See 4 for more details.