Moved some of the SrcMLArchive code into a new GeneratorArchive class. This will help with the implementation of the new DataArchive class.
Renamed the XmlFileNameMapping to AbstractFileNameMapping and made it more general.
Merge branch 'ExpressionParsing' of https://github.com/abb-iss/SrcML.NET into ExpressionParsing
Renamed ShortXmlFileNameMapping to ShortFileNameMapping and made changes to make it more general.