Added SourceFile class to store file information.
Added unit test for SourceFile class.
Added interface IIssue.
Added issues to SourceFile.
Added addIssue to SourceFileTest.
Added interface IDetector.
Added clone class to store the parse tree and the source file.
Implemented clone class.
Added unit test for Clone class.
Replaced ParseTree with Clone.
Renamed DuplicatedCodeDetector to DuplicatedCodeDetectorVisitor.
Added DuplicatedCodeDetector skeleton.
Removed param for detect method.
Added DuplicatedCodeIssue.
Added unit test for DuplicatedCodeIssue
Added DuplicatedCodeDetector.
Replaced DuplicatedCodeDetectorVisitor with DuplicatedCodeDetector.
Hide DuplicatedCodeVisitor for other packages.
Added ISolver interface.