Legacy MxCore::getYawPitchRoll() now layers on top of Orientation.
Add a special case to Orientation for handling yaw-only transforms.

git-svn-id: http://osgworks.googlecode.com/svn/trunk@517 c67418bc-a6eb-11de-8ba5-91705c1537ed
Fix for right- versus left-handed angles in MxCore::getYawPitchRoll.

git-svn-id: http://osgworks.googlecode.com/svn/trunk@518 c67418bc-a6eb-11de-8ba5-91705c1537ed
Adding possible future regression tests.

git-svn-id: http://osgworks.googlecode.com/svn/trunk@519 c67418bc-a6eb-11de-8ba5-91705c1537ed