Variables in text boxes do not get replaced

[caring-coder]

Originally posted by @t-oster in thombergs/docx-stamper#97 (comment)

[dallanmc]

I created a new pull request to show you how I had approached this issue.
#48
As you can see there is actually less code in the new branch. I have got rid of some of the co-ordinates stuff, which I don't believe we need.