perldelta for overload caching bug fixes
perldelta for overload fallback inheritance
perldelta for ‘no overload "invalid"’ warnings
perldelta for pos %foo
perldelta for while(each %h)
perldelta for undef *_, &CORE::time crash
Close the filehandle actually being tested in uni/readline.t
(Also allows the tempfile() to be unlink()ed :-)
Lookup overloaded assignment operators when trying to swap the arguments

This is in the case where we search for an overloaded operator when
passing the AMGf_assign flag (we're executing an assignment operator
like +=).

At the very beginning of Perl_amagic_call, if the flag AMGf_noleft is
not passed, we first try to look up the overload method corresponding
to the assignment operator, then the normal one if fallback is
authorized. However, if this fails, when trying later to find
overload magic with the arguments swapped (if AMGf_noright is not
passed), this procedure was not used and we looked up directly the base
operation from which the assignment operator might be derived.
As a consequence of what an operator like += might have looked
autogenerated even when fallback=>0 was passed.

This change only necessitates a minor adjustment in lib/overload.t,
where an overloaded += method wasn't corresponding semantically to the
overloaded + method of the same class, which can be seen as a
pathological case.
Synchronise Module-CoreList in Maintainers.pl with teh CPAN
mk_PL_charclass.pl: Don't use \w, \s

Now that these are partially compiled into the Perl core, we have a
chicken and egg problem if one changes.  Instead, use the \p{}
equivalent which doesn't have this problem.
Experimentally add VT to \s definition

This commit is the minimal necessary to get \s to match the vertical
tab.  It is being done early in the 5.17 series in order to see what
repercussions there might be from doing this.

It may well be that we decide that this change will require a 'use
feature' to activate.  In any event there is significant documentation
of the behavior without the VT that this patch does not address at all.

Tom Christiansen asked Larry Wall why \s did not include VT, and
reported that Larry replied that he did not remember, but had no
objections to adding it.
perlfunc: Add reference to simple folding docs
doio.c: Add some comments
embed.fnc: Change formal param name to match docs

This is purely so that perlapi will be accurate in this regard.
utf8.h: Comment improvementes, white-space
utf8.h: Simplify expressions

These expressions, while valid, are overly complicated in order to make
it easy to separate out problematic code points in the future, such as
surrogates.  But we made a decision in 5.12 to not go in that direction,
but to accept such problematic code points in general.  I  haven't
heard any cause to regret that decision; if we ever want to go back, the
blame log will easily allow us to.
utf8.h, pp.c: Add UTF8_IS_REPLACEMENT macro, and use it

This should speed things up slightly, as it looks directly at the UTF-8
source, instead of having to decode it first.
utf8.c: Extra branch to avoid others in the typical case

This test eliminates all code points less than U+D800 from having to be
checked more than once, at the expense of an extra test for code points
that are larger
utf8.c: Remove unnecessary validation

These two functions are to be called only on strings known to be valid,
so we can skip the validation.
utf8.c: Skip extraneous function call

This eliminates an intermediate function call by calling the base level
one directly.