Noted that installing custom callbacks results in undefined behavior for toll-free bridged objects accessed from Objective-C.

Updated Toll-Free Bridged Types to discuss object lifetimes with ARC.

Minor update to artwork.

Updated to remove obsolete references.

Included a link to the memory management article from the "Object References" and "Naming Conventions" sections.

Correction of minor typographical error.

Converted existing Core Foundation documentation into topic format. Added revision history.