Create Power Source Design

[kburgon]

Create the following types of power sources that all have similar functionality:

• Variable power source (like a solar panel, etc.)
• Fixed power source
• Power storage unit

[kburgon]

I included both the power source and the power storage objects in one module, and I have kept them pretty similar. There are some differences between the storage object and the source objects, though, and I'm not sure there is really a good way around this. I think we will want the algorithm to know the difference between these two types of objects that distinctly. We can discuss details and potential improvements on Monday.