* rearrange local libxml-2.0.vapi copy, split into separate patches and try to get upstream
* renamed Xml.ScannerFull to Xml.HashScannerFull
* waf: look in our own vapi/ for custom libxml-2.0.vapi
* discard libxml-2.0.vapi and libxml2.patch from patches/, as we now keep a local copy in vapi/
* update waf to 1.7.0, update wscript from bitrot, update gtk to 3.0 from 2.0
* update test cases to use GXmlDom namespace; add ValaLibxml2Test, testing our bindings
* add ValaLibxml2Test.vala to wscript_build so it can be built with waf; add ../vapi to vapi_dirs so we can find our custom libxml-2.0.vapi
* bump libvala dependency to 0.16 from 0.14
* bump gee from 1.0 to 0.8 (that's actually an increase, but their versioning scheme changed)
* autotool change?  This happened automatically, but keeping it
* update NodeListIterator for gee interface changes (to Iterator and new Traversal)
* update GListNodeList to handle new Traversable interface
* make the two NodeListIterators share a common class and reduce duplicate code
* make ChildNodeList implement Gee.Traversable
* various cleanups
* let waf compile code again using gee-0.8 (former gee-1.0)
* correct order of interfaces or else get run time error
* No, Iterators shouldn't cycle, which I mistakenly believed after discovering first had been removed and reading the documentation for valid.
* implement append_child for Document to make it easier to create a Document from scratch
* add override modifier to append_child in Document