XML tag ending in a colon

[ashawley]

@hosamaly noted in #94 that tags ending in colon aren't understood by the Scala compiler.

scala> <x:></x:>
<x:></x:>
<console>:1: error: in XML literal: name cannot end in ':'
       <x:></x:>
          ^
<console>:1: error: in XML literal: '>' expected instead of '<'
       <x:></x:>

scala> <x:/>                    
<x:/>
<console>:1: error: in XML literal: name cannot end in ':'
       <x:/>

From my reading of the XML standard, it seems like colon should be allowed as an ending character.

https://www.w3.org/TR/2008/REC-xml-20081126/#NT-Name

Unlike #94, the parser in Java has no problem accepting them.

scala> scala.xml.XML.loadString("<x:/>")
scala.xml.XML.loadString("<x:/>")
res0: scala.xml.Elem = <x:/>

scala> scala.xml.XML.loadString("<x:></x:>")
scala.xml.XML.loadString("<x:></x:>")
res2: scala.xml.Elem = <x:/>

[ashawley]

Like #94, there's no big need to fix this.