A bunch of code styling changes, as well as a few additional exceptions being thrown in error conditions.
Moved the CollisionShapeManager to the physics namespace.  Also started adding save/load shape methods for xml (in addition to binary .bullet files).
Finished implementing the XML load/save methods on the CollisionShape manager.
Minor doc fix.
Added the ability to fetch the proxies creator to the base WorldProxy class that must be implemented by all proxies.  Updated existing audio proxies.
Merge branch 'master' of https://github.com/BlackToppStudios/Mezzanine