Line breaks at the end of block elements should be escaped

Hi! The following (Confluence) XHTML syntax:

<h1>Title<br /></h1>

Leads to the following XWiki syntax:

= {{id name="MySpaceHome-Title"/}}Title
 =

Which produces two titles (the second one is empty). These events are generated:

```
beginHeader [1, HTitle]
onWord [Title]
onNewLine
endHeader [1, HTitle]
```

Which seems correct. It looks like the line break inside the heading should be escaped.

See also a likely related issue reported at https://forum.xwiki.org/t/table-breaks-when-converting-from-html/16859/2 where, with the HTML syntax, if a line break is at the end of a table cell, the rendering of the table breaks in a similar way.