More Normal Types for triplanar

The triplanar shader has a new parameter normal_type which can be used to select the type of normal to use for selecting the dominant axis for texturing. The options are shading, which is the previous behavior and uses the smooth shading normal (this normal includes bump), smooth_and_displaced is like the shading normal but without the bump, and finally smooth_before_displacing gives the smooth normal before displacement and bump. Note that smooth_before_displacing requires that autobump be enabled. (ARNOLD-15523)