Controls rebinding and pause menu!

Many changes to the latest patches, condensed into this one:

• Added tutorial section that teaches basic controls and movement;
• Added pause screen with settings and option to return to main menu;
• Added control rebinding screen with support for joypad and keyboard + mouse.

Balance changes:

• Made building enemy in warehouse parking lot less tanky (20 to 15 HP each);
• Made first boss less tanky (400 to 200 HP).