svn merge -r 70080:70711 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-18-3-Viewer

Pick up last minute patches to the viewer from 1.18.3 final release.
* Final release notes and version numbers
* SL-55123 Mac app icon missing from open source tarball (missed from previous merge?)
* SL-55121 Mac mouse cursors missing from open source tarball (missed from previous merge?)

(I believe the previous merge in this series, r70180, only committed changes inside indra. I've scrubbed the history of that range and don't see any other missing files other than the two assemblies/ patches noted above)