provide launching of solver "circuits"

[mmckerns]

should have the ability to construct logic circuits of solvers (in  DAKOTA, they are called strategies). Strategies, or circuits, provides the control flow for multiple iterators and models. Thus, solvers can be launched in parallel or series, may be nested, or configured to interact in many other ways.

[mmckerns]

basically, an API for nested optimizers is needed

the batchgrid and scattershot optimizers will be the first of these, but something more general is desired.