Add span info to XML dump
Add span info to XML dump

For a node, add span information for the label, value, and node overall if
it is present in the tree. The resulting XML looks like

  <node label="..." file="..." path="...">
    <span for="label" start="..." end="..."/>
    <span for="value" start="..." end="..."/>
    <span for="node" start="..." end="..."/>
    <value>...</value>
  </node>

ptoscano/augeas,GeoffWilliams/augeas,jasperla/augeas,hercules-team/augeas,dafugg/augeas,raphink/augeas,mlichvar/augeas,kunkku/augeas,mlichvar/augeas,kunkku/augeas,ptoscano/augeas,pevalme/augeas,pevalme/augeas,ptoscano/augeas,lutter/augeas,lutter/augeas,jasperla/augeas,manandbytes/augeas,manandbytes/augeas,mlichvar/augeas,jtopjian/augeas,MikaelSmith/augeas,jtopjian/augeas,mchf/augeas,jjlin/augeas,mchf/augeas,jjlin/augeas,lutter/augeas,hercules-team/augeas,raphink/augeas,MikaelSmith/augeas,dafugg/augeas,jjlin/augeas,kunkku/augeas,pevalme/augeas,GeoffWilliams/augeas,dafugg/augeas