Norma v0.5.0

Changelog since v0.3

• Input is no longer automatically lower-cased.
• Interactive mode is currently not available since it conflicts with recent
  changes to parallelization.
• Python bindings:
  • Normalizers now return Result objects instead of tuples.
  • Provide a new class NormaCfgParser that can automatically instantiate
    normalizers according to a supplied Norma configuration file.
• Better parallelization of normalizer calls, which should result in slightly
  better runtime performance.
• Modularized the normalizer components: normalizers are now plugins that are
  dynamically loaded. This means users can write their own normalizers without
  having to recompile Norma itself.
• Lots of bugfixes and code refactoring.