Update to 0.53

Upstream changes:
0.53    2013-09-01 17:50 UTC
        This is a maintenance release. The code contains no functional change.
        Satisfied users of version 0.52 can skip this update.
        + Fix : [RT #86338] : typo fix.
                Thanks dsteinbrunner@pobox.com for the patch.
        + Tst : Author tests are no longer bundled with this distribution.
                They are only made available to authors in the git repository.

0.52    2012-11-05 02:30 UTC
        + Add : The new constant VMG_COMPAT_SCALAR_NOLEN evaluates to true
                when your perl does not call 'len' magic for scalars, which
                is the case for perl 5.17.4 and above.
                This fixes RT #80388.
        + Tst : t/35-stash.t has been taught about perl 5.17.4.
        + Tst : Author tests overhaul.

0.51    2012-08-18 15:00 UTC
        + Fix : It is now safe to call dispell() from inside 'free', 'copy' and
                'uvar' callbacks to dispell the magic currently in use.
                Thanks Clinton Gormley for reporting.
        + Fix : Exceptions thrown from inside a 'free' callback are now always
                consistently propagated outside of the callback. They used to
                be lost when the 'free' callback was invoked at the end of an
                eval block or string.
        + Fix : The 'reset RMG flag' workaroundn used to allow wizards with
                both 'uvar' and 'clear' magics to be cast onto a hash, has been
                made thread-safe.

0.50    2012-06-24 23:00 UTC
        + Fix : Less memory is leaked when a wizard is freed during global
                destruction, or when an exception is thrown from a 'free'
                callback.
        + Fix : [RT #77991] : t/17-ctl.t fails on perl 5.14 and 5.16.
                This was actually an issue with ActivePerl, and this test
                has learned to cope with it.
                Thanks Gisle Aas for reporting.
        + Tst : t/35-stash.t has been taught about perl 5.17.1.
        + Doc : Many clarifications.

0.49    2012-06-05 21:40 UTC
        This is a maintenance release. The code contains no functional change.
        Satisfied users of version 0.48 can skip this update.
        + Fix : [RT #77644] : t/17_ctl.t fails in test 44 since 5.17.0.
                This test has been taught about perl 5.17.0.
                Thanks Reini Urban for reporting.
        + Tst : t/99-kwalitee.t will be skipped when only problematic versions
                of its dependencies are available.

(wen)