XMLUnit.NET 2.9.2

This is a small feature and bugfix release.

The full changelog is

• added NodeFilters#SatisfiesAll and SatifiesAny methods to make it easier to combine multiple node filters.
  added to simplify the use case of xmlunit/#249

• when documents contained element content whitespace represented by System.Xml.XmlWhitespace the types and methods that are supposed to strip or normalize whitespace would fail.
  Issue #38