Keys in first page headers are not replaced

[sweco-sekrsv]

I was having a issue with keys not being replaced in a header. This is a first page header.
I noticed that you already fixed a issue with headers earlier here: #4

However that fix does not fix replacing keys in a first page header.

I fixed my problem by adding
paragraphs.extend(Paragraph._get_paragraphs(section.first_page_header))
to the
paragraph.py
get_all(doc) function

This seems to work fine with my document. You might want to test it and add it to the library. I attach a docx where you can see the problem.
hello_first_page_header.docx