Use bold underline and italics within invoice description

@elouera - note, however, that not all of these will work when you generate a PDF. For example, the in-built PDF exporter doesn’t seem to support <u>underline</u> but it does support <b>bold font</b>.

You may be able to work around any issues like this if you use an external PDF generator (install the PDF generator, and then use Print from Manager instead of the PDF button).