I'm documenting that `xcodeGUITricks` is only required when the project has Swift.
I'm documenting that `xcodeGUITricks` is only required when the project has Swift.

That may or may not be true (there's some debate about symbols support) but somebody
can re-open and/or file a new issue in that case.

Documenting the use of `xcodeGUITricks` for non-Swift projects has confused people
since it doesn't currently work on those projects.

Close #12

drewcrawford/CaveJohnson,kiancheong/CaveJohnson