.Net and Commandline MailMerge for docx NuGet Package

MailMerge replaces simple and complex merge fields in WordProcessingML .docx files
and helps you apply .Net's Xml & XPath tooling to Word documents.

Component Usage For Streams or Files:
```
var (outputStream, errors) = new MailMerger().Merge(inputStream, Dictionary);
var (ok,errors) = new MailMerger().Merge(inputFileName, Dictionary, outputFileName);
```
Extension Methods & Helpers for working with OoXml
```
stream.AsWordprocessingDocument(isEditable)
stream.AsXPathDocOfWordprocessingMainDocument(isEditable)
stream.AsXElementOfWordprocessingMainDocument(isEditable)

stream.GetXmlDocumentOfWordprocessingMainDocument()
fileInfo.GetXElementOfWordprocessingMainDocument()
fileInfo.GetXmlDocumentOfWordprocessingMainDocument()
```
A NamespaceManager, NameTable & Uri which you need when creating an XmlDocument
and/or XElements:
```
var xdoc = new XmlDocument(OoXmlNamespaces.Manager.NameTable)
var xelement= mainDocumentPart.CreateElement("w", "t", OoXmlNamespaces.WpML2006MainUri)
```
CommandLine Usage: Perform a merge, or show a document's Xml
```
dotnet MailMerge.dll inputFile1 outputFile1 [inputFileN [...outputFileN]] [ key=value [...] ]
dotnet MailMerge.dll --showxml file [fileN ...]
```.