XSD imports don't take include into account

[dedsm]

By trying to use sekken with the travelport API Release 8.0 (https://support.travelport.com/webhelp/uapi/Content/Getting_Started/Universal_API_Schemas_and_WSDLs.htm) I noticed the CommonReqRsp.xsd includes (not imports) the Common.xsd file, and sekken ignores this, I could handle this by copying the entire Common.xsd contents (minus few lines) into the CommonReqRsp.xsd and everything works as expected.