FPS Demo - Fixes 1

I made some changes based on watching other people play.

Features

• Touching a wall will slow the player's fall momentarily
• Arrows have been added to the first room to guide the player on how to double jump, ledge jump, and wall jump

Fixes

• The game should better adapt to various zoom levels and screen sizes
• The game should more easily take control of the mouse when pressing the Escape key