title: Add additional xsd schemas with libXml2
body: <p>I have a xml and schema which I want to validate. I don't want schema to be stored in file, but in database location. I use <code>xmlSchemaNewMemParserCtxt</code> to parse the schema. The problem is that this schema references another schema for basic types: <code>&lt;xs:include schemaLocation="CommonTypes.xsd"/&gt;</code>, which libXml2 searches in the current working directory. Is there any way to supply these additional schemas in memory buffer? </p>