adding XHTML file extension as an XML grammar
adding XHTML file extension as an XML grammar

dvingo/atom-beautify,prettydiff/atom-beautify,Glavin001/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,dvingo/atom-beautify,Glavin001/atom-beautify,dvingo/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,prettydiff/atom-beautify,Glavin001/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,Glavin001/atom-beautify,janmolnar/atom-beautify,prettydiff/atom-beautify,prettydiff/atom-beautify,janmolnar/atom-beautify,Glavin001/atom-beautify,dvingo/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,janmolnar/atom-beautify,dvingo/atom-beautify