Some proposed allowable exceptions to SwiftLint rules

[jrturton]

Code generated by Xcode should be treated like open source files, and have a disable-all added at the top. I'm thinking particularly of core data property generated files, which are never touched by the user.

Code in unit tests should be allowed to use IUOs, since test code is dealing with known state and defensive coding would often add too much noise and detract from the meaning of the tests.