hessenberg/schur order of outputs

Maybe there is a good reason for the current ordering, but otherwise I'd like to request that the schur function return its outputs in a different order.

The hessenberg function returns its outputs so that (v,s) = hessenberg(c) gives v*s*v' = c. In contrast, the schur function returns its outputs so that (u,r) = schur(c) gives r*u*r' = c. The order that the hessenberg function returns its outputs seems more natural (to me), but consistency across the two functions would be nice.

Start by reading the hessenberg and schur function APIs and their documented output conventions. Check how each function's returned values are used before deciding whether a consistent ordering is feasible. Done means the intended ordering is agreed and the affected API behavior and callers are updated consistently.

Written by the indexing model from the issue text.