With this change, all the plug-ins and frameworks can be built in one
command (xcodebuild from the command-line, or "Build" from Xcode).
This requires that you have one common "Built Projects" folder, which is a
given if you do any work with frameworks. See Xcode Preferences,
Building, and choose "Place Built Products in..." "Customized location".
Note that since I'm building on an Intel Mac, I have removed
"CompositorAV" from the Plug-Ins, since it requires a PPC Mac.