Different types of bullets

[johneastman]

The user can shoot different types of bullets. For example:

• a bullet that bounces off the edges of the map (a set number of times?)
• a bullet that, upon hitting a target circle, splits the circle into multiple smaller circles
• fire multiple bullets in different directions

Note: each of the above should be their own issue/task.

User can switch bullet type with keyboard input.

[johneastman]

Issues:

• https://github.com/johneastman/Circles/issues/11
• https://github.com/johneastman/circles/issues/15
• https://github.com/johneastman/circles/issues/22

[johneastman]

New issues will be added for different bullet types.