swift234

Runtime: Start implementing a default Mirror for ObjC classes.

For ObjC classes, use class_copyIvarList to walk the ivars, and produce the summary string using -debugDescription. Still to come:

- visiting the base class as a child, and
- calling -debugQuickLookObject to get the quicklook object. Still waiting on a final design for the IDERepresentation API.

Swift SVN r14626