XmlElement test

Had a problem that a XmlAny type (XmlElement[]) could not be parsed
Generics null check and ICollection added

null check for GetTypeWithGenericsInterfaceOf(typeof(IEnumerable<>)
and make ICollection behave the same as IEnumerable
Make ICollection behave the same as IEnumerable
Merge pull request #1 from WimAtIHomer/patch-1

XmlElement test
added missing return
Make ICollection behave the same a IEnumerable
Added ICollection test

Also added extra Assert in IEnumerable test
Merge pull request #361 from WimAtIHomer/master

Added XmlElement test and possible fixes to fix test