Several bug fixes in testProperties.cpp, the biggest one being a missing _ in front of _nWantedVals, which prevented the plugin from working
- use const char* instead of char* for constant strings
- more generally, constify a bit
- use OpenFX constants instead of strings when available (e.g. kOfxImageEffectSimpleSourceClipName instead of "Source")
add OpenFX headers to xcodeproj
fix warnings
add ofxUtilities.H to xcodeproj