Pulled up 'algorithmName' attribute
Pulled up ModelExplanation and ModelVerification elements
Maintaining a stack of parent elements via Visitor#pushParent(PMMLObject) and Visitor#popParent()
Moved Visitor implementation classes from 'org.dmg.pmml' package to 'org.jpmml.model' package
Added unit test for visitor design pattern
[maven-release-plugin] prepare release 1.1.9
[maven-release-plugin] prepare for next development iteration
Updated version information