Spec clean-up
    
    - Reinstate compatibility with older distributions like EL-5
    - Drop -tests subpackage (general lack of interest in this), but include
      them as documentation for the main package
    - BR: perl(MRO::Compat) for testing if we're not bootstrapping
    - Don't use macros for commands
    - Make %files list more explicit
    - Filter unwanted requires and provides
    - Use tabs