fixes getTieEndX in Stave (StaveModifiers placed at the end of the Stave collide with StaveTies without end notes.)

[rvilarl]

Fixes #489

StaveTie › No End Note

before:

after:

No other visual difference

[rvilarl]

@0xfe @mscuthbert this one is minor it should be a minute to merge it.

[0xfe]

Thanks Rodrigo. Does this change anything if there's no stave end modifier? Does the tie still reach the end of the stave?

[rvilarl]

It does not produce any other visual change. Is there already a test for what you refer to? I am not sure that I really understand the case.

[0xfe]

Is there a test where the Tie begins on the last note and there's nothing on the right? (That's what the 'No End Note' test should have been, but it seems like it now ends with a stave modifier.) In that case, the tie should hit the right stave barline.

[rvilarl]

@0xfe I have added two tests related to cases without note and without Clef both at start and at end.

I believe that the output is correct:

[rvilarl]

@0xfe hopefully ready to merge

[0xfe]

Looks great, thanks for adding those tests!