Half Done Exercise 70 - Equivalent Binary Trees

Implemented the Walk function to traverse the binary trees and return
the result through a channel. However, unless the channel is closed by
the goroutine (in this case, the Walk function), the runtime freaks out
that the goroutine is deadlocked. So I had to make another Walk function
called WalkSubtree that actually does the tree walking. The original
Walk function just calls the WalkSubtree function and closes the
channel. It was impossible to make the Walk function recursive and close
the channel inside it without making it overly complex.
Completed Exercise 70 - Equivalent Binary Trees

I decided to create 4 trees, two seeded with 1 and two seeded with 2.
Those with the same seeds should be the same and no combination of
mismatched seeds should ever be the same. The results prove this.