New types of enemies

[kdhageman]

Ideas:

• [ ] Suicide ships
• [ ] Slow, tanky ships
• [ ] Ships with an actual shield attached. These shields need to be destroyed first before the ship can be damaged. Unprotected parts of the ship could be damaged though.
• [ ] Non-ship enemies (such as sea creatures)
• [ ] Stationary structures on land (such as catapults)