Multi timestep prototyping

[Samuel-amap]

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[Samuel-amap]

Preliminary comments after some basic testing.

• Having connectors as ad hoc, user-written models is slightly awkward, since they need access to the current timestep and handle it directly, but no other models require it (it's a simulation parameter). It is possible -but not ideal- to write a model that provides the timestep but not ideal. Adding it to the statuses could be an option, but may be error-prone in ways that may be hard to infer depending on how the user manipulates their weather data.

• The default timestep is a global simulation parameter (which may or may not be inferred from the weather data), but any other timesteps that differ from the default are model-specific.

• Scale is required when specifying a timestep mapping whenever there may be ambiguity (example : model used at two different scales, which has a variable timestep-mapped in both cases, to variables with different names. Only with the scale can one tell them apart).