Parameter global refactoring/cleaning #57
Description
Parameterized protocol
Current infrastructure is way more complex than necessary. We have params, params_names, optimisation_params(_dict), etc. What we really need is an ordered mapping. Mapping to provide the names, ordered to ensure the flattened representation is deterministic. Then we can have some utilities that turn that mapping into whatever shape is useful.
Parameter protocol
A parameter should be a simple protocol. It needs a value, a way to set that value from a flattened representation, and its size. The size is useful for the sparse case where we need to know how many values belong to a given parameter.