fixed #47.

[rosslamont]

• Added some test cases around well-formedness checking. Motivation was
  to better understand and document well-formedness checking.
• Significant improvements in documentation, including clarification of
  includes and excludes elements, validation configuration, particularly
  around well-formedness and the "validating" flag.
• Enhancement of documentation formatting to improve clarity
• Some additional hyperlinking from generated documents (mojo report)
  to expose the more detailed documentation available from the usage page.