Renouncing to check only at the end of the call to "apply in" the
absence of remaining dependent evars when several arguments are given.
For simplicity of implementation, checking instead for every step of
the n-ary "apply in".
American spelling + layout in CHANGES.
Updating CHANGES (evars as ident).
Adapting output tests to current naming of evars, even if unclear
where it will eventually stabilize.