Add new check Forbid private type as method return type check.
Add simple test
Add test and message for check
version was bumped to 1.8.0
Add check to checkstyle plugin xml
Remove processing private method.
Some code fixs
Add check for wildcards
Review functions on bottom and make them as static if possible.
Some minor fix.
Add check zero class set size in finish tree.
Add comments to tests.
Fix style.
Minor style fix.