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.

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.

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.

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.

GenericEditors now check their "selected" status before asking to be deleted.

The FilterViewport pauses for 50 ms after deleting a processor in order to
avoid double-deletions.

Previously, if you placed a sink in front of a source, it would lead to
a never-ending "while" loop. By removing two lines (254-255), this problem
was solved.

Generic Editors colors now match the type of processor.
The FilterViewport layout has been changed to a simple outline.

- Added a FilterViewportButton class to the UIComponent file, which shows/hides
the FilterViewport whenever it's clicked
- Thus, the DataViewport can now fill up almost the entire window