Added MTLManagedObjectAdapter and mtl_invertedTransformer

Faster reflection

Initial stable release

Actually fix secure coding

Report MTLModel initialization errors, secure coding fixes

Backwards-compatible <NSSecureCoding> support

Replace external representation concept with model adapters

Expecta/specta/build settings updates, -mtl_anyObjectPassingTest:

MTLEqualObjects, BOOL NSValueTransformer, memory management fixes

Added armv7s to iOS architecture list