Currently, if you construct a diffeomorphism from a manifold to itself, you have to specify the manifold as the codmain. With the changes in this ticket, this is no longer necessary and we assume that the user want's to specify a self-diffeomorphism if no codomain is given.

CC: @tscrim @nthiery @mjungmath @egourgoulhon @mkoeppe

Component: manifolds

Author: Tobias Diez

Branch/Commit: 54d4cd3

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/31323