Non-Regression Tests for my recent layout changes

[jimnelson372]

I added tests to the non-regression test directory for changes I made in pull requests #1773, #1774, #1777 and #1780.

These were for issues #1680, #1679, #839 and Forum posted issues 18832 and 18816.

I also included the example you provided in #1777, which is in the test SequenceLayout_0006_Test. That one, plus a few other right side note test I now have, would have alerted me to problems with changing ArrowAndNoteBox. Enough of these tests will be very helpful.

A few of them do not fail when I roll back my code changes for testing. These seem, therefore, to have been bugs primarily in the drawing logic rather than the layout positioning that was generated in the test results. These were my tests:

• ComponentExtraArrows_0001_Test -- which was about missing message extra arrows (when LEFT or UP) on component diagrams reported from Forum issue 18816 and change in Fixes Forum reported: Text arrow rendering in component diagrams seems partly broken #1773.
• SequenceLayout_0004_Test -- which was about the short arrow case from Forum issue 18832 that was part of Fixes #1680, #1679, #839 and various other Sequence Diagram layout issues. #1777.

Still, I decided to keep those two, just in case other changes are caught by these tests. I suspect with some future layout fixes some of these tests will fail due to the improvement rather than a regression, but at least we'll have the opportunity to examine the change in any failed test conditions to make sure they were intended.

Regards.