There is a method to the image naming madness!

Images are named as category_name.png, where the category is optional.
Category and name both do not contain any _'s.

Current categories include: prefs, volume, setup

If the icon is general, no prefix is required. If a general icon is not 
suitable for your needs, add a prefix to a more appropriate a new icon.

Name icons identically between hxplay and realplay. Avoid using "helix" or
"real" in the icon name, particularly if it will be present in both builds.

Some of the reasoning here:
- By putting the category first, the image list shows up sorted with related 
  icons grouped together
- Leaving off the prefix encourages use of that icon in areas other than
  that dictated by its prefix -- ie, I can use pause.png in the main player or
  any of the various embedded player controls. Calling it main_pause.png would
  be misleading.
- When in doubt, don't prefix icons. eg - tactoggle.png is probably not 
  going to be useful ouside of the embedded player, but it is also unlikely
  to collide with anything in the main player that would need to redefine
  that icon, so it is fine as is, plus that makes it consistant with the
  other controls that go into the embedded player.
- Re: everything lower case -- this makes renaming icons a little easier if 
  moving from case sensitive OS's to insensitive ones -- doesn't hurt, and
  follows the lead of most other open soure projects
