Create functions for doing non-in-place running of plugins
(to be used exclusively by mixer plugins)
Clean up the plugin format by removing some unused cruft...
Refactoring of a plugin API member...
Deprecate all references to send volume and begin prepping for plugins
to do the job...
Add the widgets for the mixer...
Hook the mixer peak meters into the peak meter callback.
Add a mechanism for adding and removing plugin widgets from the mixer.
Re-use the existing plugin infrastructure for mixer plugins, just extend
the plugin* array to accomodate the sends.
Oops..  the limit is 4, not 5...
Slightly narrower peak meters...
The mixer is starting to look like what I envisioned for it, albeit I'm
currently struggling with goofy Qt layout resizing issues...
Random tidying up before I attempt some really big stuff...
Initial work on using the regular plugin mechanism for the send plugins...
Random mixer stuff...
Use a brute-force approach to drawing the mixer and redraw at every
change...  It works somewhat as intended now, minus the layout resizing
issues and that the plugin processing isn't implemented yet.
Fix most of what's wrong with the mixer...  Still a few bugs to squash,
but the success of this feature branch is now imminent...
Enough fixes to merge the mixer branch (but still more TODOs left...)