Fix get current matrix warnings + allow query current Orientation Matrix 

Two matrix stack related commits:

b5cca6f : fixes compiler warnings by adding a default case to getCurrentMatrix, as discussed with @bilderbuchi in https://github.com/openframeworks/openFrameworks/commit/150e1972ab9c1f1ba0a8b420db70341990c2e6fe#commitcomment-6204050

e8da01f : extends getCurrentMatrix to allow querying the current orientation matrix stack. I found this extension necessary in a current project where i had to do calculations with current projection matrix but found that because openFrameworks post-applies an orientation matrix to the projection matrix i had no access to the correct, *oriented* projection matrix my shaders were using.