Create convenience method
Update release notes
Add addNewReference to ReferenceList
Improve method signature
Clean up
Fix StatementTest
Fix formatting
Merge pull request #187 from wmde/addreference

Create Statement::addReference
Also remove the SimpleSiteLink class alias
Merge pull request #236 from wmde/ssl

Also remove the SimpleSiteLink class alias
Remove old Statement constructor
Add serialization compat test
Fix Statement constructor
add serialization compat test (again)
Remove serialization compat test

Serialization of statements is broken anyways.