Fixes #472

Fixes high cpu usage with gtk2-suil hosts

This is very useful for carla-single

Closes #479

Closes #473

Fixes #438

Closes #441

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

Fixes #402

Hopefully doesn't break linux/osx stuff...

Was a threading issue, uiIdle() being called from 2 threads.
Fixes #418
Fixes #227

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.

Closes #409