build fails if Xcode is not /Applications/Xcode.app

[stevehartwell]

The build assumes /Applications/Xcode.app to link against IDE framework(s), which is usually true but not always--Xcode.app is completely self-contained so it works fine if it's renamed or in another location.

You can get the path to the currently running Xcode through various build environment variables.

Thanks for making this very nice plugin!