Spec clean-up
    
    - Can run spelling test unconditionally now
    - BR: perl(ExtUtils::Manifest)
    - Don't BR: perl(Test::Perl::Critic) if we're bootstrapping
    - Use %{_fixperms} macro rather than our own chmod incantation
    - Run developer tests in a separate test run
    - Drop redundant %{?perl_default_filter}
    - Don't use macros for commands