Remove PartSpec and use reflection

[db47h]

For custom components, what if we did something like this:

type Mux8 struct {
    In  [8]int `hw:in`
    Sel int    `hw:in`
    Out [8]int `hw:out`
}

func (m *Mux8) Update(c *Circuit) {
    // ...
}

// Along with a Component interface
type Component interface {
    Update(c *Circuit)
}

And use reflect to get the specs of a part. Chip.mount could then instantiate parts as needed and init their input/outputs.

[db47h]

Working prototype: https://gist.github.com/db47h/de370b53213766c4890a3f7afcb83253

[db47h]

The prototype works with PartSpec. Plus it's les flexible than PartSpec:

Cons:

• Flexibility: How to implement the simple gates without a lot of boiler plate code?

Pros:

• No need to implement PartSpec.Mount
• Cleaner

[db47h]

Merged 34622ac