Sync core with CPAN version.pm release

Remove pointless diag lines, which were more trouble than they were
worth.  Add code to ensure that SV's with magic are handled properly,
and include a test for it as well.  A couple of whitespace changes and
one last set of I32 -> SSize_t upgrade for array indices.
version has been upgraded from version 0.9903 to 0.9904