Minor fixes and improvements

This is the first release after the GMTK game jam has closed. It has a bunch of smaller bug fixes and improvements based on the feedback I got from people who played the game.

• Added a pause menu to the game
• The “Wave starts” and “Wave ends” popups no longer block the screen
• Decreased the collider sizes of all objects and characters in the game
• You can now skip the initial cutscene
• Lock the direction of ranged enemy projectiles to the point when the enemy takes aim, instead of when they shoot
• Enemies tied together are now pulled close together and stay as one tied group
• Fixed melee attack distance, enemies can now hit folks again