This allows to special-cases session-specific control-surface state.
e.g. midi-learn.
Only restore midi-learned, session-specific, bindings when loading a
session with generic-midi enabled.
Also dis/re-enable generic-midi resets midi-learned, but no other
session-independent settings.
This also handles the edge case:
1) load global config, generic-midi = ON, w/ bindings.
state is remembered as cpi->state
2) load session-condig, generic-midi = OFF, cpi->state is retained
3) user enables the surface, cpi->state from (1) is applied.
-> invalid bindings applied -> fail
Robin Gareus
b6b353d452