Add syntax highlighting to markdown 2 PDF converter

Probably would have to make a JS build for a puppeteer page, using the prism highlighter. And making it so you can customize the theme by passing in the theme name.

Convert md2pdf:

```
task convert -I md -O pdf -i ../file/base/document/example.md -o test/hold/example.md.pdf --style-text-color ff0000
```

See the readme Development section for details on codebase structure.