Laundry list of inter-peer wire protocol changes

In a mailing list conversation from January 29, 2016, Rusty Russell and AJ discussed the shachain construction. Russell suggested constructing an n-way tree structure similar to how the elkrem tree is visualized. He stated that a 64-deep binary tree is a 64-dimensional 1x1...x1 hypercube, but using a tree structure would be less confusing. AJ then provided a spanning tree for a hypercube which outlined the 4d hypercube and described how to get to the hash for 10 using SHA256. The subtrees are self-similar, and extending past 2**n means adding a new branch off from 0. Python code for generating the graph was also attached.