Replace dot with underscore in HTML name

[pkozul]

I used docx-templates to generate a Word document with embedded HTML (altchunks). I was unable to open the document using Docx4j. The following error was reported:

org.docx4j.openpackaging.exceptions.Docx4JException: For source /word/document.xml, cannot find part word/template_document.xml_html1.html from rel html1=template_document.xml_html1.html
        at org.docx4j.openpackaging.io3.Load3.getRawPart(Load3.java:626)
        at org.docx4j.openpackaging.io3.Load3.getPart(Load3.java:372)

After unzipping the Word document, I noticed there were a bunch of files in the word folder that were named like this:

template_document.xml_html1.html
template_document.xml_html2.html
template_document.xml_html3.html

Since each file name contained two dots in it, I renamed them by replacing the first dot with an underscore:

template_document_xml_html1.html
template_document_xml_html2.html
template_document_xml_html3.html

After renaming the files, I zipped up the folder, and was then able to open the Word document in Docx4j.

This pull request contains a single line of code to ensure the first dot in the HTML file name is replaced with an underscore. Not sure if the file names could end up with multiple dots, so a regex global replace would probably be a better solution.

[jjhbw]

While this sounds to me like a bug in docx4j instead (these are valid filenames AFAIK), this is a simple enough change to implement on our side. Merged manually. Thanks.