Center HMD HUD and magnifiers on default eye position
Fix similar problem for HMD third person view

getUprightHeadPosition() changes with avatar lean.
Remove unused methods
Fix some build warnings while in the vicinity
Minor adjustment to Oculus pick ray calc
Adds AudioDevice mute functionality to ScriptEngine
Merge pull request #3732 from thoys/20166

CR for Job #20166 - Extend AudioDeviceScriptingInterface to have muted property and mute event
Merge pull request #3735 from ctrlaltdavid/20126

CR for Job #20126 - Rift HUD shouldn't move with head