* Unicode support for the embedded Perl5 bridge. (This takes effect iff
the embedded Perl supports SvUTF8_on, typically Perl 5.8+.)
- Source code in eval('...', :lang<perl5>) can now contain non-ASCII
characters; they are treated as if "use utf8;" is in effect.
- Str objects passing from Pugs land into Perl 5 are always turned
into SvUTF8_on unicode strings.
- Strings passed from Perl 5 to Pugs land are always converted into
Unicode Str objects for now; this may be relaxed once we have a
native Buf type in Pugs land.
- Both named and unnamed regexes now assumes Unicode semantics.
* Use New()/Safefree() instead of malloc()/free() in p5embed APIs.
* Use svpvn and CStringLen instead of svpv and CString, so strings with
embedded nulls can be safely passed either way.
* In non-embedded builds, call binmode(STDIN, ':utf8') only on
Perl 5.7 or later.
