Stopped ZNGMessage from repeatedly creating its attributed string, even when content had not changed.  An NSAttributedString will now persist as long as the number of loaded images is consistent.
Stopped ZNGMessage from repeatedly creating its attributed string, even when content had not changed.  An NSAttributedString will now persist as long as the number of loaded images is consistent.

Zingle/ios-sdk,Zingle/ios-sdk,Zingle/ios-sdk