increase version number
avoid use of defined-or operator

The defined-or operator // wasn't introduced until Perl 5.10. This
commit hopefully fixes the test suite on older perls.
validate subroutine arguments with Params::Validate
allow the user to specify options for action class constructors
reduce usage of BAIL_OUT
prefer croak() to barf()
use Class::Load instead of eval "require $class"
v0.009

 - it is now possible to pass additional arguments to action class constructors
   when specifying actions; the only additional argument so far is the type of
   the output piddle, allowing you to write, e.g.,
      my $binner = PDL::NDBin->new(
         axes => ...,
         vars => [ [ var => { class => 'StdDev', type => \&PDL::float } ] ],
      );
   to get the standard deviation in type 'float' instead of the default type
   'double' (Edward Baudrez)
 - try to make the tests run under Perl 5.8 (Edward Baudrez)
 - other minor fixes (Edward Baudrez)
prepare for next release
v0.010

 - release on master branch instead of development branch; no changes