pdf generation doesn't handle complicated headings properly

[jeromesimeon]

Describe the bug
Transform to pdf does not handle heading with complex content properly, losing some of the content and internal markup.
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:
Try to transform the following markdown to pdf:

This is a
*complicated*
heading
==============

Here is some text

Using Markus:

bash-3.2$ markus transform --from markdown --to pdf --output test.pdf --input test.md 
10:37:32 AM - info: Creating file: test.pdf
10:37:32 AM - info: 
<binary pdf data>

This results in the following pdf:
test.pdf

The result should be consistent with the rendered markdown:

[jeromesimeon]

Fixed in #337

Fix handles table of content. For instance on the new test/data/contract.md

Containing a heading 2:

Title2
*(Heading Two)*
**on several lines**
----

Properly generates a TOC: