projectGenerator generates unusable Xcode project

[bangnoise]

Using current HEAD, current OF HEAD, current OS X, current Xcode

1. Clone the ofxSyphon addon into addons
2. Launch PG
3. Select ofxSyphon as an addon
4. Hit Generate Project

The resulting project can't be opened by Xcode, giving the following error:

Project [snip]syphon_test/syphon_test.xcodeproj cannot be opened:
 -[PBXBuildFile group]: unrecognized selector sent to instance 0x7ff7e3b26fb0

[bangnoise]

Maybe dup of #63 but affecting OS X, not iOS