Now, when the user clicks on a tab in the DataViewport, the corresponding Editor becomes
active. Likewise, when the user selects an Editor with a Visualizer, the corresponding
tab becomes active in the DataViewport.

Channel selection now takes place within a slick new interface. It's not
yet tied to actually changing parameters, but things should be much simpler
code-wise, as well as visually.

The AudioComponent now closes the audio device when it's not in use,
saving CPU cycles. Previously, background CPU levels would be between
8 and 10%. Now, when acquisition is not active (and audio device settings
are not being actively edited), background CPU levels drop to 2%. More
optimization will be necessary to get it down to zero, but 2% is still
a big improvement over what we had previously.

UIComponent, ProcessorGraph, etc. were still referencing the configuration
class (but not using it). Those references have now been removed, as the
configuration object will be replaced by a set of parameter and channel
objects.

Whenever files are needed for recording, the RecordNode opens them. When
they are no longer necessary (either recording has stopped, or recording
of a particular channel has stopped), the RecordNode closes them.

If continuous channels are toggled for recording within their respective editors,
a "writeContinuousBuffer" function will be activated within the RecordNode. This
function doesn't do anything yet, but it will make it easy to add diskwriting
capabilities in the near future. Once a stable format for events has been established,
a similar function will be implemented for writing event buffers to disk.

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.