Upstream changes:
version 0.003; 2010-04-10
* bugfix: in pure-Perl implementation, make sure ambient package (from
which require is invoked) is passed on correctly to the code in the
required file, on those Perls where it is so inherited
* in XS, use macros to avoid explicit passing of aTHX, in the manner
of the core
* in XS, avoid using "class" as a variable name, for compatibility
with C++ compilers
* make all numeric comparisons against $] stringify it first, to avoid
architecture-dependent problems with floating point rounding giving
it an unexpected numeric value
* in Build.PL, explicitly declare configure-time requirements
* add MYMETA.yml to .cvsignore