Renamed Avatar to ScenePresence to avoid clash with libsl Avatar class.

Added ThirdPartyLicenses folder containing the licenses for the various third party libraries we use.
Plus some other small changes.

ThirdPartyLicenses/libsl.txt

@@ -0,0 +1,23 @@
+Copyright (c) 2006, Second Life Reverse Engineering Team
+All rights reserved.
+
+- Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+ 
+- Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+- Neither the name of the Second Life Reverse Engineering Team nor the names
+  of its contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+ 
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.