Add ol.xml.isDocument
Use ol.xml.isDocument in ol.format.XML
Use ol.xml.isDocument in ol.format.KML
Add ol.xml.isNode
Use ol.xml.isNode in ol.format.XML
Use ol.xml.isNode in ol.format.KML
Cope with undefined baseURI in ol.format.KML
Add ol.xml.getLocalName
Use ol.xml.getLocalName in ol.format.KML
Don't use problematic afterLoadXml function
Don't use getResponseXml() on IE
Add FIXME to remove afterLoadXml