Update Classes hierarchy reference documentation
Update Classes hierarchy reference documentation

- Reflect the introduction of the new MantisSourceGitBasePlugin abstract
  base class.
- Add SourceGitphp

dregad/source-integration,mantisbt-plugins/source-integration,make-all/source-integration,mantisbt-plugins/source-integration,dregad/source-integration,dregad/source-integration,make-all/source-integration,make-all/source-integration,mantisbt-plugins/source-integration