Dreadnaut support

doc/oper.xml

@@ -1899,7 +1899,7 @@ fail
     the <E><A>k</A>-closure of <A>digraph</A></E> is defined to be the unique
     smallest symmetric loopless digraph <C>C</C> with no multiple edges on the
     vertices of <A>digraph</A> that contains all the edges of <A>digraph</A>
-    and satsifies the property that the sum of the degrees of every two
+    and satisfies the property that the sum of the degrees of every two
     non-adjacenct vertices in <C>C</C> is less than <A>k</A>. See <Ref
     Prop="IsSymmetricDigraph"/>, <Ref Prop="DigraphHasLoops"/>, <Ref
     Prop="IsMultiDigraph"/>, and <Ref Oper="OutDegreeOfVertex"/>. <P/>

gap/io.gd

@@ -55,4 +55,6 @@ DeclareOperation("DiSparse6String", [IsDigraph]);
 DeclareOperation("PlainTextString", [IsDigraph]);
 DeclareOperation("WriteDIMACSDigraph", [IsString, IsDigraph]);
 DeclareGlobalFunction("WritePlainTextDigraph");
+DeclareOperation("WriteDreadnautGraph", [IsString, IsDigraph]);
+DeclareOperation("ReadDreadnautGraph", [IsString]);
 DeclareGlobalFunction("DigraphPlainTextLineEncoder");