* Unify headers already sent errors
Now whenever we need to check where headers were already sent in
ext/session, we call a single location that prints where, keeping it
consistent output wise.
* Unify session aready started errors
Similar to the one for headers.
* Also change session active checks too
This usually go hand in hand with the headers already sent checks, but
is in a separate commit because of the amount of tests it changes.
These hopefully test a reasonable set of basic, error and variations for
the twenty or so session functions. Note however that they do not
test all the session configuration settings, nor do they test anything
with register_globals enabled.
Calvin Buckley