Inner HTML elements are processed after the tail text

[HiromuHota]

Describe the bug

In tests/data/html_simple/md.html, <em>italics and later <strong>bold</strong></em>. Even is processed in the following order:

1. italics and later
2. . Even
3. bold

This is illustrated in #12 too.

To Reproduce
Steps to reproduce the behavior:

1. Run tests/parser/test_parser.py::test_parse_md_details and set a breakpoint

Expected behavior

The said sentence is processed in the following order:

1. italics and later
2. bold
3. . Even

Environment (please complete the following information):

• Fonduer Version: [0.7.0 and master(3d5392c)]

Additional context
Add any other context about the problem here.

Why this happens?

When the node is <em>italics and later <strong>bold</strong></em>, node.text (=italics and later ) and node.tail (=. Even) are processed, the next node <strong>bold</strong> is processed.

[senwu]

So, the expected order should be (1) node.text, (2) text in the inner node, and (node.tail)?

[HiromuHota]

I think so.
This is especially true when you want to align words between HTML and PDF (related to #12).
I don't think this is a major issue, though.