UI Update (Pongus 0.1.1)

Minor update to improve user experience.

Features:

• Hints moved from holding CTRL to holding Tab for sake of familiarity
• Forgot to add Space button for shooting in "Defence" mode*
• Added a neat fade effect in main menu
• Added tinted background on pause screen
• Language buttons are now switches (stays pressed after click)
• Changed ammo counter in "Defence" mode
• Change HP counter in "Defence" mode to healthbar
• Fixed ammo overload**

* it was mentioned in hint, but wasn't working until patch
** Ammo counter would display 10 even if you have more than that