Quest System

Added the Quest System!

The Quest system shows you how to make a simple quest system.

Player walks up to the NPC, the NPC tells the player their quest, the quest UI shows up, the player kills the slimes, when the slimes are all dead the quest text changes, when the player comes near the NPC the NPC thanks them.

Also includes a small segment about creating a fence with only 1 sprite, firing bullets, holding a kill count, and how to make text look better!