First pass at a meta_generator option for Moose::Exporter

First pass at a meta_generator option for Moose::Exporter

    This vastly simplifies and perfects code in the
    MooseX::Role::Parameterized package. meta_generator lets MXRP
    future-proof against changes in Moose::Role, and gives *current*
    error messages from Moose::Role instead of continuing to produce
    the 0.60 era messages.