Camera - Constrained first-person

This camera script provides constrained first-person rotation in both the spin and pitch axes.

Note: This is not a replacement for the regular first-person camera - do not attach this to the Player GameObject. It is meant for situations where the player is e.g. sitting down, and can only rotate a certain amount.

Steps to use: ConstrainedFirstPersonCamera.cs:
 * 1) Paste the code below into a C# script named ConstrainedFirstPersonCamera.cs
 * 2) Using AC's Scene Manager, create a new SimpleCamera
 * 3) Attach the "Constrained First Person Camera" component to the new SimpleCamera
 * 4) Configure the fields as desired
 * 5) Assign the camera in the normal way, i.e. through the "Camera: Switch" Action or as the scene's default