Support for replacement patterns and html in header and footer

Problem/Motivation

Hi,

I'm very happy to have found this module, I've tried everything else on the market and this is the only module that so far, seems to work very well. Thanks a bunch!

I'm trying to setup PDF printing of Purchase orders and Invoices. These kinds of documents generally benefit from a nice, multi-column header and footer. I've tried adding HTML and fields values from the view ({{ title }}) but it seems like currently the header and footer only accept plain text. I'd like to suggest HTML and replacement pattern support for headers and footers as a new feature.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes