Implemented the visitor feature.
Added the covariant out keyword.
Documented the IContainerVisitor interface.
Documented the Accept method.
Slightly modified the xml document

of IContainerVisitor.
Added some scenario test for the customization

feature provided by visitor.
Removed the parameter names.
Committed the trivial modification.
Introduced the CompositContainerVisitor class.
Extracted the IdiomaticTestBase class.
Added idiomatic tests to CompositContainerVisitor.
Implmented the CompositContainerVisitor class.
Renamed IdiomaticTestBase to IdiomaticTest.
Improved the CompositContainerVisitor class.
Addressed the code analysis warnings.
Documented the CompositeContainerVisitor class.
Slightly refactored the test types.
Added the scenario test

for CompositeContainerVisitor.
Addressed the code analysis warning.
Incremented minor version

to indicate that the container visitor is a new feature.