Move Expression::doInline and Statement::doInline into visitor classes
Move Statement::interpret into a visitor
Merge pull request #3263 from yebblies/doinline

[DDMD] [refactor] Move Expression::doInline and Statement::doInline into visitor classes
Merge pull request #3267 from yebblies/statementinterpret

[DDMD] [refactor] Move Statement::interpret into a visitor