Try to send FX parameter feedback even if REAPER not informed about change

[helgoboss]

e.g. when changing Zebra2 preset using its GUI

[helgoboss]

Mmh, no IReaperControlSurface callback at all. Asked Justin if he could add one because REAPER seems to get notified at least of the preset name change.

[helgoboss]

Justin suggested GetProjectStateChangeCount() but this doesn't increase when e.g. changing Zebra2 preset using its GUI, so another dead end.

Turns out, CSI just uses polling which of course works.

Let's equip ReaLearn with an option to also use polling for the few targets that don't work reliably with REAPER's "notification system":

• FX: Set parameter value (doesn't work with REAPER's own notification system if it's a monitoring FX or when switching presets within some plug-in GUIs)
• Track: Enable/disable FX
• Track: Show/hide
• FX: Enable/disable
• Send: Mute/unmute

That also means we need to check if the feedback value would change (save previously calculated value).

[helgoboss]

On this occasion, hide checkboxes "Send feedback after control" and "Prevent echo feedback" of feedback disabled.

[helgoboss]

Implementation:

• Add "Poll for feedback" to targets that don't support automatic feedback or not in all situations.
• Enable it by default without additional JSON, also for old presets.
• Only send feedback if polled target value has changed.
• Don't send all feedback on play/resume. That fixes the shaking/nervous motor faders.