Problem:
- There's not yet a way to get the parameters for each channel
after it's clicked

Although it has not been rigorously tested for all cases.

The control panel now holds an "AudioEditor" to adjust volume
and open a window to alter device settings. Audio output is definitely
working, but different buffer sizes make it sound really weird. The
same problem is present in the Juce demo app, however, so I don't
think it's a problem inherent in the GUI.

Major modifications to EditorViewport::loadState() and
EditorViewport::saveState() allow complex signal chains to be loaded
and saved. There are still some issues with editor button status
on startup, but these should be easy to fix.

But they won't do anything useful until the ProcessorGraph is updated

The EditorViewport now contains buttons to scroll through multiple tabs,
or scroll across long signal chains. Now, there can be infinitely
many signal chains of infinite length (if you have a lot of time
on your hands).

Functions for managing the signal chain are no longer handled by
the EditorViewport, but by the SignalChainManager

Three important changes:
- The FilterList is now the ProcessorList
- The FilterViewport is now the EditorViewport
- Any classes that need to access important UI objects have become subclasses
  of the "AccessClass". Such objects automatically obtain pointers from
  the UIComponent and register the MessageCenter as an ActionListener. This
  will make it much easier to allocate pointers to objects.

The DataThread shouldn't have a MML all the time, but it does need it
when signaling that the data source is not found.

Also fixed a line in the FilterViewport that was causing the enabled
status of editors to fail to update.

The reason between the UI interactions with the DataThread was simple: it
was using a type of lock that's meant for interacting with the UI.

This seemed to fix all the issues with dropped samples, but we'll still
have to run it through more rigorous tests in the future.

Processors used to have their sample rate and inputs/outputs set when
their source/dest nodes were set. Now, this step doesn't occur until
after the signal chains are constructed. So far, this seems to make
things run much more smoothly.

It was a float vs. int problem!