Fixes #569

Fixes #552

Closes #559

Fixes #472

Fixes #438

Closes #445

Only clamp outputs if plugin includes supportsStrictBounds feature,
and an output port does not set hasStrictBounds.
That case means the plugin needs strict bounds support from the host,
and does not set bounds for a port.

In the case of an output port with hasStrictBounds,
it's considered an error if the value is not really in bounds.
We won't check for this though (err, moo moo...).

Fixes #383

This buffer is used for the UI thread, which runs slower than RT.
The buffer can fill very quickly, and it's only cleared during
the main thread.
So, increase this buffer in a reasonable amount to compensate.

This allows to run the new LSP plugin UIs.

This helps #387, but rule is defined by the plugin.
Later on the user must be able to choose the scale mode
(among other things)