Reorganize unit tests

Updates in the source module:

• Refine comments
• Remove warnings
• Ensure naming consistency

Updates to accommodate tests:

• ConnectionDialog.java: initialize the fields
• AbstractAxisCanvas.java: call parent's dispose method
• CanvasAxisY.java: add color to allow more levels

Updates in the test module:

• Ensure name consistency
• Add unit test for remote connection dialog
• Add unit test for user-derived metrics
• Reorganize unit tests to avoid duplicates
• Refine and update code comments

Signed-off-by: Laksono Adhianto laksono@gmail.com