Endless Demo Update MK.III

MK.III Changes:
General Changes:

• Rebuilt Weapon Attachment Buffs/Debuffs system (Stat Effects on players & enemies will come later.)*
  
• Added Harder variant enemies**
• Added an option to turn on/off hud.
• Added validation on the tutorial text explaining melee, should now show the bound melee key instead of the default key.
• Added a simple Loading screen.
• Removed the enclosed middle train car in "Runaway Train" to improve the flow of the level

• Fixed loadout screen showing weapons are still locked despite being owned or being high enough level.
  
• Fixed enemies only reacting to the centre of the player and not the head/camera. (If there's issues with NPCs not reacting to the player, please let me know.) 
• Fixed attachment benefits disappearing after changing weapons. 
• Fixed Combo attachment benefits not applying to weapons that were not currently equipped if they also had Combo attachments.
• Rewrote the attachment price calculations so most shotgun shell door prices are no longer cost $0.

• *Added a hud element that shows the currently equipped weapons buffs.
  
• **Harder variant enemies will start spawning in endless after wave 20. 
• Increased the kill combo penalty multiplier when taking damage. (x2 > x5)