Bogus <br> is inserted after nested table

[Piotrek Koszuliński]

1. Open any sample.
2. Insert table (with cell padding and cell spacing set to 0).
3. Place caret inside table cell.
4. Insert next table (with cell padding and cell spacing set to 0).

• Expected: Nested table fills entire outer table cell.
• Actual: There's free space at the bottom of table cell. It's caused by bogus <br>.

This behaviour was helpful in v3, but in v4 we can use magicline to place caret after the table.

Perhaps more cases may be find in which we create unnecessary paragraphs/bogus brs to allow caret positioning.