Include Electronics in spec_helper to avoid repeating it
Rename pin to terminal
Add terminals to components as array of strings or symbols

Terminals
- requires components
- knows what components they belong to
- has no voltage
Add Node
Terminals add through nodes

- Nodes are re-used if possible
- Nodes links to terminals and vice versa
Components require a circuit
Only allow connection within circuit
Call Circuit#analyze after each connection
Remove unnecessary use of namespace