AutomatableModel: added isAtInitValue()
AutomationPattern: do not put initial value if model is at init value

There's no need to initialize an automation pattern with the value of the
model if it's default already. This fixes tons of dummy automation patterns
being saved for every note (as part of the note detuning feature).
AutomationPattern: coding style
InlineAutomation: improved hasAutomation()

Pprevent saving inline automation if there's just one value which equals
value of model which is going to be saved anyways.
NotePlayHandle: only use detuning automation if it exists at all
Note: create DetuningHelper objects on-demand

Instead of creating a DetuningHelper instance for every note (which sums
up to thousands of AutomationPatterns) create them on-demand when opening
automation editor or loading settings.