Add graph references

references/igraph-1.0.1/tests/unit/gml.out

@@ -0,0 +1,79 @@
+===== graph1.gml =====
+Creator "igraph"
+Version 1
+graph
+[
+  directed 1
+  AttOne "x"
+  AttTwo 3.14
+  node
+  [
+    id 1
+    b "2"
+    c 5.6
+    nan ""
+  ]
+  node
+  [
+    id 2
+    a 2
+    b "asd"
+    d -Inf
+    nan "foo"
+  ]
+  node
+  [
+    id 5
+    b ""
+    nan ""
+  ]
+  edge
+  [
+    source 5
+    target 1
+    weight -0.45
+    label "-0.45"
+  ]
+  edge
+  [
+    source 2
+    target 5
+    label "Tom & Jerry's "friendship""
+    num1 Inf
+  ]
+]
+======================
+
+===== graph2.gml =====
+Creator "igraph"
+Version 1
+graph
+[
+  directed 1
+  node
+  [
+    id 0
+    Foo ""
+  ]
+  node
+  [
+    id 1
+    Foo ""
+  ]
+  node
+  [
+    id 2
+    Foo "bar & baz"
+  ]
+]
+======================
+
+===== graph3.gml =====
+Creator "igraph"
+Version 1
+graph
+[
+  directed 0
+]
+======================
+