Added rank comparison to Statement::equals

-> 71554
Merge pull request #269 from wmde/statementequals

Added rank comparison to Statement::equals
Add tests for Statement::equals
Fix $message param in Statement not equals test
Merge pull request #270 from wmde/statement-equals

Add tests for Statement::equals
Update namespace for PropertyNotFoundExceptionTest

this is not Wikibase Lib!
Merge pull request #273 from wmde/propertynotfound

Update namespace for PropertyNotFoundExceptionTest
Introduce the StatementListProvider interface

So that it's possible to use type hints to recognize whether
something can hold Statements.
Update StatementListProvider.php
Merge pull request #274 from wmde/StatementListProvider

Introduce the StatementListProvider interface
Update release notes for StatementListProvider
Make exception error message style more uniform.
Merge pull request #276 from GPHemsley/exceptions

Make exception error message style more uniform.
Fix copy pasta.
Merge pull request #277 from GPHemsley/typos

Fix copy pasta.
Remove undefined var
Stop Statement requiring a Claim