feat(library/tactic/proof_state): remove goal name when pretty printing the proof state

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/library/tactic/proof_state.cpp

@@ -16,7 +16,7 @@ format proof_state::pp(formatter const & fmt, options const & opts) const {
             first = false;
         else
             r += line();
-        r += group(format{format(p.first), colon(), line(), p.second.pp(fmt, opts)});
+        r += p.second.pp(fmt, opts);
     }
     return r;
 }