Global preset and interaction with default values

As has been previously discussed several times with Jamoma (including @jln- ) and with @evanmtp @navid and @petervanhaaften (and also in #595) it might be interesting to possibly and eventually fuse the default and preset systems.

As is described in the mockups below, the idea would be to have a global preset system, with an init preset, that would be fired once all models are loaded.
It would work this way, by going from the global preset (held by the [ossia] object and/or [ossia.device] objects, down to each model's preset, recursively, and down to each parameter's default value - for each parameter:

• first look if a value is present in the global preset, use this one, and ignore all values "below"
• if not, then look into the preset of each model (and then sub-model), if a value is present, use the most top-level one
• if no value is present in presets, then use the default value
• if no default value, don't do anything
• fire all chosen values, for all parameters, by order of priority, recursively (don't fire anything for parameters without a preset or default value)

Does that make sense ?

I'm putting some diagrams about this that we did a few years ago with the Jamoma team

Start by reviewing the mockups referenced in the issue and the prior discussion in #595, then trace the existing [ossia] and [ossia.device] preset and default-value behavior. Define how initialization should traverse global presets, model presets, sub-models, and parameter defaults, including priority and firing order. Done means the behavior and implementation scope are agreed before coding.