Fix typos. (#1829)

dump.cpp

@@ -4,7 +4,7 @@
 
 /*
 	Basic idea: provide concepts that define the interface(s) to different kinds of graphs so that you can do
-	basic graph operations and algoriths without knowing exactly which kind of graph it is and keep ignorant
+	basic graph operations and algorithms without knowing exactly which kind of graph it is and keep ignorant
 	about implementation details.
     
     Basic design idea: do like the STL
@@ -227,4 +227,4 @@ void use1(Tree& t, Dag& d, Dgraph& dg, Node_ref& tr, DAG_vertex_ref& dr, Gnode_r
   traverse(t,tr);
   traverse(d,dr);
   traverse(dg,gr);
-}
+}