Examples do not call dotty

- Only create graphic files to better use gitpod
- Add unix history dot file

examples/examples.rb

@@ -77,7 +77,7 @@ def bfs_example(g = cycle(5), start = g.detect { |x| true })
 end
 
 # Would like to have GraphXML here
-def graph_from_dotfile (file)
+def graph_from_dotfile(file)
   g = RGL::AdjacencyGraph.new
   pattern = /\s*([^\"]+)[\"\s]*--[\"\s]*([^\"\[\;]+)/ # ugly but works
   IO.foreach(file) { |line|
@@ -94,21 +94,23 @@ def graph_from_dotfile (file)
   g
 end
 
-# ruby -Ilib -r examples/examples.rb -rrgl/dot -e'bfs_example(module_graph,RGL::AdjacencyGraph).dotty'
-
+# ruby -Ilib examples/examples.rb
 if $0 == __FILE__
   require 'rgl/dot'
 
   dg = RGL::DirectedAdjacencyGraph[1,2, 2,3, 2,4, 4,5, 6,4, 1,6]
-  dg.dotty
   dg.write_to_graphic_file
-  bfs_example(dg, 1).dotty
-  bfs_example(graph_from_dotfile('dot/unix.dot'), 'Interdata').dotty({ 'label' => 'Interdata Nachfolger', 'fontsize' => 12 })
 
+  # BFS tree from 1 of dg:
+  bfs_example(dg, 1).write_to_graphic_file('png', 'bfs_example')
+
+  # Unix history as a graph:
+  g = bfs_example(graph_from_dotfile('examples/unix.dot'), 'Interdata')
+  g.write_to_graphic_file('png', 'unix', { 'label' => 'Interdata Nachfolger', 'fontsize' => 12 })
+
+  # Modules included by AdjacencyGraph:
   g = module_graph
   tree = bfs_example(module_graph, RGL::AdjacencyGraph)
   g = g.vertices_filtered_by { |v| tree.has_vertex? v }
-  g.write_to_graphic_file
-  g.dotty
+  g.write_to_graphic_file('png', 'module_graph')
 end
-

examples/unix.dot

@@ -0,0 +1,53 @@
+/* courtesy Ian Darwin and Geoff Collyer, Softquad Inc. */
+digraph unix {
+size="6,6";
+	"5th Edition" -> "6th Edition";
+	"5th Edition" -> "PWB 1.0";
+	"6th Edition" -> "LSX";
+	"6th Edition" -> "1 BSD";
+	"6th Edition" -> "Mini Unix";
+	"6th Edition" -> "Wollongong";
+	"6th Edition" -> "Interdata";
+	"Interdata" -> "Unix/TS 3.0";
+	"Interdata" -> "PWB 2.0";
+	"Interdata" -> "7th Edition";
+	"7th Edition" -> "8th Edition";
+	"7th Edition" -> "32V";
+	"7th Edition" -> "V7M";
+	"7th Edition" -> "Ultrix-11";
+	"7th Edition" -> "Xenix";
+	"7th Edition" -> "UniPlus+";
+	"V7M" -> "Ultrix-11";
+	"8th Edition" -> "9th Edition";
+	"1 BSD" -> "2 BSD";
+	"2 BSD" -> "2.8 BSD";
+	"2.8 BSD" -> "Ultrix-11";
+	"2.8 BSD" -> "2.9 BSD";
+	"32V" -> "3 BSD";
+	"3 BSD" -> "4 BSD";
+	"4 BSD" -> "4.1 BSD";
+	"4.1 BSD" -> "4.2 BSD";
+	"4.1 BSD" -> "2.8 BSD";
+	"4.1 BSD" -> "8th Edition";
+	"4.2 BSD" -> "4.3 BSD";
+	"4.2 BSD" -> "Ultrix-32";
+	"PWB 1.0" -> "PWB 1.2";
+	"PWB 1.0" -> "USG 1.0";
+	"PWB 1.2" -> "PWB 2.0";
+	"USG 1.0" -> "CB Unix 1";
+	"USG 1.0" -> "USG 2.0";
+	"CB Unix 1" -> "CB Unix 2";
+	"CB Unix 2" -> "CB Unix 3";
+	"CB Unix 3" -> "Unix/TS++";
+	"CB Unix 3" -> "PDP-11 Sys V";
+	"USG 2.0" -> "USG 3.0";
+	"USG 3.0" -> "Unix/TS 3.0";
+	"PWB 2.0" -> "Unix/TS 3.0";
+	"Unix/TS 1.0" -> "Unix/TS 3.0";
+	"Unix/TS 3.0" -> "TS 4.0";
+	"Unix/TS++" -> "TS 4.0";
+	"CB Unix 3" -> "TS 4.0";
+	"TS 4.0" -> "System V.0";
+	"System V.0" -> "System V.2";
+	"System V.2" -> "System V.3";
+}