Created a Two-second Spawn Delay at the Beginning of Each Level

- Added the spawn delay in EnemySpawning.cs so that enemies start spawning after the Level Start animation
- Reset the spawn delay timer when a new level starts
- Fixed a bug in which an enemy could still be spawned on the frame the level ends. This results in the enemy being spawned before the spawn delay in the next level. Fixed this by moving the call to void CheckEndLevel() to the end of Level.cs' Update method
Created 2 recolors of all the enemies

-Made enemies spawn with a random recolor
-Modified the Game Over Sprite to include recolors and a Ranged Goblin
Merge branch 'EnemyRecolors' into InitialEnemySpawnDelay
Merge branch 'InitialEnemySpawnDelay'