Support DOCTYPE or ignore it please

[notsyncing]

Hello, I'm using xmldoc to parse XML files and it worked very well!
But I ran into a problem...
when a XML document contains a DOCTYPE tag and there are more than one tag after it, xmldoc will throw an error, like following:

var a = new xmldoc.XmlDocument("<b /><a></a>")
TypeError: Cannot read property '_opentag' of undefined
at Object.parser_opentag as onopentag (/home/sfc/Projects/common-js/node-bubble/node_modules/xmldoc/lib/xmldoc.js:222:41)
at emit (/home/sfc/Projects/common-js/node-bubble/node_modules/xmldoc/node_modules/sax/lib/sax.js:625:33)
at emitNode (/home/sfc/Projects/common-js/node-bubble/node_modules/xmldoc/node_modules/sax/lib/sax.js:630:3)
at openTag (/home/sfc/Projects/common-js/node-bubble/node_modules/xmldoc/node_modules/sax/lib/sax.js:814:3)
at Object.write (/home/sfc/Projects/common-js/node-bubble/node_modules/xmldoc/node_modules/sax/lib/sax.js:1189:26)
at new XmlDocument (/home/sfc/Projects/common-js/node-bubble/node_modules/xmldoc/lib/xmldoc.js:188:15)
at repl:1:9
at REPLServer.defaultEval (repl.js:132:27)
at bound (domain.js:254:14)
at REPLServer.runBound as eval

docs like "" and "" do not produce this error.

Could you please add support for DOCTYPE tags, or just ignore them sliently?
Thank you very much!

using xmldoc 0.3.1 on nodejs 0.12.7

[notsyncing]

Found problem, XML doesn't support mutiple root elements...
Sorry for disturbing!

[nfarina]

👍