SplishSplash and DualSPH for the dam break scenario

[sarmento]

As a user of the current dam break demo, I have the need to show investors that it is possible to seamlessly change the underlying simulator without changing anything else on my code, except the simulator parameter. This is a major selling point of the API because it allows us to show we are not stuck to a specific provider of simulation (and so we are not in a fragile business position that we depend on a single point to expose a certain functionality). I need to be able to show we can do this:

sim_output = scenario.simulate()

which runs with some default simulator (and which the user doesn't have to select but we will inform the user via a status message), but also:

sim_output = scenario.simulate(engine="splishsplash", device="gpu")

or

sim_output = scenario.simulate(engine="dualsphysics", device="cpu")

the feedback messages should show that we are running with these options, and the output should be syntactically the same so that the rest of the code does not change.

This is an urgent feature since it allows us to show a very important aspect of the API

Note: I would like this to be implemented by Luis+Begaiym with only distant supervision from Fabio.