This PR makes PDDLStream optional for tests, and also updates to the main PDDLStream repo.
It also shuffles around some of the import code so that users get a more readable error message when they try to import the PDDLStream planner and don't have the module available.
This PR makes PDDLStream optional for tests, and also updates to the main PDDLStream repo.
It also shuffles around some of the import code so that users get a more readable error message when they try to import the PDDLStream planner and don't have the module available.