Constraints at intermediate times

[ocots]

          The example provided in this [tutorial](https://infiniteopt.github.io/InfiniteOpt.jl/stable/examples/Optimal%20Control/hovercraft/) have constraints on intermediate values of the state.

I guess that's not allowed in OptimalControl.
I'll look for another model to use in the comparison : https://infiniteopt.github.io/InfiniteOpt.jl/stable/examples/Optimal%20Control/consumption_savings/#Consumption-Savings-Problem

Originally posted by @0Yassine0 in control-toolbox/CTBenchmarks.jl#21 (comment)

[PierreMartinon]

Hi there,
Nope, but it could be an extension of 'setPointConstraints' which currently enforces the boundary constraints at initial and final time, and the constraints on the optimization variables. The main question is how to define/pass the relevant data. The intermediate times could be inserted into the normal time grid since we support non-uniform grids.

Another option could be to use an interpolation to approximate the state at these times, which may be less interesting for this particular case, but on the other hand opens the possibility of treating delay problems (as done in Bocop). Although the modeling of the dynamics would have to be extended somehow.