Yank new version of go-wish.

Has some readability improvements, and a substantial jump forward in
the vendored go-cmp library.

No major functional changes; just pretties.
Signed-off-by: Eric Myhre <hash@exultant.us>

go-wish @ 8b3e70f8

-Subproject commit 5ad1f5abf4368a7f5ae616fdbf02821b6a93bf10
+Subproject commit 8b3e70f8e83078821ecd45313039b8beb85210fc