multifile patch against blead/pod/*.pod

multifile patch against blead/pod/*.pod

I mostly fixed spelling mistakes, some of very long standing,
but a few files got more attentive word-smithying.  I've updated:

    pod/perl.pod

    pod/perldelta.pod
    pod/perl592delta.pod
    pod/perl5120delta.pod
    pod/perl51310delta.pod
    pod/perl5139delta.pod

    pod/perlfunc.pod
    pod/perlop.pod

    pod/perlrebackslash.pod
    pod/perlrecharclass.pod

    pod/perlutil.pod

    pod/perlhack.pod
    pod/perlintern.pod
    pod/perlnetware.pod
    pod/perlpolicy.pod