Clean up type converters

[sliekens]

• Change converter naming convention.
  Previous naming convention: 'ConverterForXyz'
  New naming convention: 'XyzConverter'
• Change data contract naming convention.
  Previous naming convention: 'XyzDataContract'
  New naming convention: 'XyzDTO'
• Move types into matching files
• Move initialization code to te bootstrapper.
  The bootstrapper is now reponsible for initializing converters.
• Convert internal classes to public sealed.
  This change is necessary to be able to initialize converters
  from outside their containing assembly.
• Improve argument exception messages
  When 'ArgumentException' (or a derivation) is thrown, the
  message should say what is expected instead of what isn't.
• Replace boilerplate converter code with T4 templates
  Where possible, T4 text templates and reflection are used
  to automatically generate type converters for well-known
  entities.
• Add integration tests

Resolves: #7
See also: #5