Resolve "Align Checkstyle versions used by Eclipse and Maven"

Closes #16 (closed)

• Aligned Checkstyle versions used by Eclipse and Maven.
• Updated also AsciiDoctor Maven plugin versions.
• Checkstyle configuration updates.
  • Added some new checks that all hold on our code.
  • Configured some existing checks to check other constructs as well.
  • Configuration written by new Checkstyle version.
• Fixed some non-matched
• tags in JavaDoc.
  • These were newly detected by Checkstyle.