Update to 0.8.6

Fixes for firstChild property for both XmlElement and XmlDocument when
dealing with text, CDATA, Comments, or Processing Instructions as the
first child of a node.

Adjust of getElements* functions to always return an array, even when no
elements were found.

Various typos fixed.
Update to 0.8.6
Merge branch 'master' of https://github.com/videlais/xml-for-cocoonjs

Conflicts:
	src/xml-for-cocoonjs.js