Merge all of the patches made to Branch_1-15-1 back into release:

* Release notes for 1.15.1(3)
* Updated contributors list
* Revert apr libraries (NOTE: Also done in maintenance, this should be a no-op...)
* Fix for SL-42640 Entering appearance mode triggers "items coming too fast"
* Fix for SL-42257 Mute Resident button does not open the user picker

svn merge -r 61568:61569 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release
svn merge -r 61585:61586 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release
svn merge -r 61601:61602 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release
svn merge -r 61761:61762 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release
svn merge -r 61777:61778 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release
svn merge -r 61805:61806 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release
svn merge -r 61824:61825 svn+ssh://svn.lindenlab.com/svn/linden/branches/Branch_1-15-1 --> release