Generic Gun class

[saricden]

[Problem]

It would be good to have a generic Gun class we can extend from to create new weapons quickly.

[Solution]

1. Create new Gun class and extend from Container.
2. Add config key/value properties w/ defaults to constructor(config).

• Projectile sprite key.
• Gun sprite key.
• Gun idle animation key (if applicable, defaults to false).
• Gun shoot animation key (if applicable, defaults to false).
• Emitter config (spread operator pass-through).
• Pistol grip v rifle x shotgun style grip.

3. Create new property for weapon in MCAfrica constructor config pass in instantiated gun.
4. Create a switchWeapon(weapon) function on our MCAfrica class.