Report LineNumber and file, when schema file could not be read

[Pretasoc]

I'm currently generation classes for schema files, which often are not valid schema files themself. It would be nice, if the tool could report the line number, on which an exception was raised, when the schema file could not be read. An error message like The 'http://www.w3.org/2001/XMLSchema:element' element is not supported in this context. is not pretty helpful on itself.

I assume you are using System.Xml.XmlSchema.Read() at some point to read the schema file. The error handler of that function already reports the line number, if applicable.

[mganss]

Good idea. Would be great if you could tackle that and create a PR.