Table ending in empty cell

[drscannell]

Currently, if the last cell of a table is empty, it will be dropped from the HTML:

| Header 1 | Header 2 |
|----------|----------|
| Cell 1   | Cell 2   |
| Cell 3   |          |

This pull request does the following:

1. Add test for situation described above
2. Fix bug causing the the last cell to not be added during conversion to HTML.

[rhiokim]

+1

[prust]

+1, also reported in #188

[utensil]

+1

[benelog]

👍

[MaXFalstein]

Is there any reason why this pull request has not been merged?

[redfast00]

+1, there is another PR for the same bug in #697

[JoshuaKGoldberg]

Ping @chjj

[joshbruce]

#980

[styfle]

Thanks for the PR but this is already fixed.
See the demo to see it working in the latest version of marked.