For some reason, grabbing the magic keyboard focus makes scroll stop working
regardless of what MRV::canvas_group_event() returns. I can't figure out any
reason to grab the keyboard in this case anyway, so I just removed it.
Also simlify MRV event handling code in general.
Shoot for roughly 30 steps for all controls.
Always keep sensible step information in ParameterDescriptor and just convert
for the UI.
This is a little weird, but it's less weird than it was before, and works.
Among other things, this means that automation controls/lists have the actual
min/max/normal/toggled of parameters, and not those inferred from the Parameter
ID, which is not correct for things like plugin parameters.
Pushing things down to the Evoral::ParmeterDescriptor may be useful in the
future to have lists do smarter things based on parameter range, but currently
I have just pushed down the above-mentioned currently used attributes.
fixes crashes:
* If the Editor-Mixer shows a channel with a plugin that
has been edited in the Mixer, double-clicking the plugin
will try to bring up a 2nd instance of the plugin-UI.
* When closing Ardour both the Mixer and the Editor-Mixer try to delete the underlying plugin, resulting in a double free.
This probably isn't correct in several ways, but it works more than it did, so
I figure it's push worthy.
Still not working:
* Saving mute automation list
* Dragged control points are not snapped to model restrictions
(boolean, in this case, but general problem)
* Line goes funny if you record mute automation
(as opposed to drawing it which works)
