Fix to LineSimilarityChecker, previously was nonfunctional.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
Refactored LineSimilarityChecker to remove code duplication

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>
Move file-related utility classes into edu.wpi.checksims.util.file

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>