Update V0_312 Complete Gameplay loop

Hi there!
In this update, I added the functionalities that allows you to complete the demo. 

You will reach a credit scene after defeating the waves of blobs in the arena!

Here are a resume of the update:

• Added Credits of the game
• Fixed issues related to spamming buttons
• Fixed issue where the gun would get the trigger of the closing door for the arena
• Tweaked the post process to look more sharp with less blooming
• Fixed multiple particle effects 
  • Muzzle flash of the shots
  • Particles of Checkpoint 
  • The end level door
• Fixed the Spawner of the arena that wouldn't reset when reloading after the death
• Added volumetric fog to give more ambiance to the game 
• Added shooting feedback for the gun (rotates faster the more the player shoots)
• Modified input for the shooting : Player can now hold the button down to shoot

I think this is all the modifications for this update! In the next update, I'll be focusing on the decorations and enhancing the general look of the game and adding a in game menu! Currently its a Gold candidate for the demo of this game. 

I hope you'll enjoy the new things!

Have a great time! :)