View Angles (Part 1 - Redux) (#1002)

* Added ViewAngle/Pitch/Roll properties to actors.

- These are offsets for camera angles that allow turning the camera without affecting aim or movement direction.
- Added A_SetView<Angle/Pitch/Roll>, which will set the view direction.
- Added ABSVIEWANGLES flag, used to make the view absolute instead of an offset.

* Converted functions to be direct-native.

src/common/engine/namedef.h

@@ -1039,6 +1039,9 @@ xx(AttackZOffset)
 xx(SpawnMask)
 xx(ScoreIcon)
 xx(ViewHeight)
+xx(ViewAngle)
+xx(ViewPitch)
+xx(ViewRoll)
 xx(FallingScreamMinSpeed)
 xx(FallingScreamMaxSpeed)
 xx(GruntSpeed)