Version 1.3: Tracked keypad and displacement map

Implements:

• An error window displaying which devices are required to run the app correctly and are currently missing;
• A tracked keypad, generated when a Vive tracker is connected and after asking the operator through interface;
• A keypad configuration system, allowing to use any keypad as a tracked one as long as it has the right keys;
• A VR device manager component alowing to have a better understanding of what is connected and its properties;
• A displacement map instead of the parallax map, with a tessellation shader for a finer displacement;
• Bump the Unity LTS version to 2021.3.18f1;
• Refactoring of the GUI prefabs (code cleanup, breakdown in several smaller components);
• Code cleanup of the managers (more complient to the coding convention).

Fixes:

• Artifacts on the runtime generated materials using a normal map;
• Crashes when a mute trial with the DAFF file specified ends.
• Dead code remaining about the audability and occlusion map properties;
• Better code for the mesh generation (and finer generation).