v0.9.1

Explain shows the graph Wire declared before it is built. go doc -all
against 0.9.0 adds no symbol and changes no signature, and an upgrade cannot
break a caller; only the rendering of an unbuilt Wire service gains lines.

Changed

• Explain draws the dependencies a Wire binding declares when it has not
  been built: dashed edges under the node, each continuing as the recorded
  tree where the dependency has been built and as a declared one where it has
  not, ending at a closure or at a key nothing provides. A declared by: line
  names the unbuilt services that declare a key, beside needed by: for the
  built ones. The output for a built service is unchanged, and Graph still
  renders only what was built.