[temp.constr] Apply wording updates to p2-4.
[various] Editorial wording fixes.
[edit] Remove ill-formed tag.
[temp.constr.atom.deduct] Explicitly define in terms of
abbreviated function templates.
[temp.deduct] Apply wording changes.

Don't talk about concept checking.
[temp.expl.spec] Use non-template function.
[temp.explicit] Explicit instantiation of members.

Only when the constraints are satisfied.
[temp.inst] Add examples for member templates.