Reverting to Xcode 4.6.3 since Xcode 5 doesn't come with gdb anymore and lldb is not properly supported in Qt Creator. Also put back the version of NSIS that we actually use. [ci skip]
Reverting to Xcode 4.6.3 since Xcode 5 doesn't come with gdb anymore and lldb is not properly supported in Qt Creator. Also put back the version of NSIS that we actually use. [ci skip]

Fairly/opencor,Fairly/opencor,mirams/opencor,Fairly/opencor,mirams/opencor,Fairly/opencor,mirams/opencor,mirams/opencor,Fairly/opencor,mirams/opencor