[V1.1] New Game Modes Update! 🎉

Issue Fixes:

1. Improved piece selection and movement;
2. Improved piece location update.

New Features:

1. Added spectator support - more than 2 players can join the game, the extra players will become viewers;
2. Added basic (western) Chess and Go support;
3. Added a nice physics simulation when pieces are killed and removed from board.

Keyboard/Interface Change:

1. Use ‘Alt+Scroll Wheel’ to zoom camera.

Credits:

1. The (western) chess background scene is from Epic Games “Particle Effects” demo, full scene is available in spectator mode, some partial collisions are added;
2. The (western) chess pieces are from RescueStudios11 on Blender Swap (https://www.blendswap.com/blend/21963), the chess board is from Rehten (with modifications) on Blender Swap (https://www.blendswap.com/blend/24490).