Update manual and error messages for new digraphs-lib repo

Author: wilfwilson

doc/utils.xml

@@ -64,7 +64,7 @@
     For these tests to complete, the digraphs library <C>digraphs-lib</C> must
     be downloaded and placed in the <C>digraphs</C> directory in a subfolder
     named <F>digraphs-lib</F>.
-    This library can be found on the &Digraphs; website.
+    This library can be found in the &DIGRAPHS_LIB; repository.
   </Description>
 </ManSection>
 <#/GAPDoc>

gap/utils.gi

@@ -196,8 +196,8 @@ function(arg...)
   if file = fail then
     ErrorNoReturn("the file pkg/digraphs/digraphs-lib/extreme.d6.gz is ",
                   "required for these tests to run. Please install the ",
-                  "'digraphs-lib' archive from ",
-                  "https://digraphs.github.io/Digraphs/ ",
+                  "most recent 'digraphs-lib' release archive from ",
+                  "https://github.com/digraphs/digraphs-lib ",
                   "and try again,");
   fi;
 

makedoc.g

@@ -94,6 +94,8 @@ XMLEntities.NAUTY := UrlEntity("nauty",
   "https://pallini.di.uniroma1.it");
 XMLEntities.EDGE_PLANARITY_SUITE := UrlEntity("edge-addition-planarity-suite",
 "https://github.com/graph-algorithms/edge-addition-planarity-suite");
+XMLEntities.DIGRAPHS_LIB := UrlEntity("digraphs-lib",
+  "http://github.com/digraphs/digraphs-lib");
 
 XMLEntities.MUTABLE_RECOMPUTED_ATTR := """If the argument <A>digraph</A> is
 mutable, then the return value of this attribute is recomputed every time it is