Solidify when to make a new component.

[sniyaz]

During the review of #567, the issue arose of when exactly we should add new components to AIKIDO. The logic in this PR is that a new component should be added when either/or:

1. The amount of code in this component has grown large enough that splitting it off makes sense.
2. The dependencies involved would mean that a large component (with lots of critical functionality) would fail to build if certain optional dependencies were not installed correctly.

We should debate and solidify these guidelines, then add them to our code guidelines.