Generate overloads without strong enums for 1.0 compat

OpenTK 1.0 and Xamarin Android/iOS do not use strongly-typed enums for
OpenGL ES. Generate overloads with the "All" enum in order to maintain
compatibility.

Source/Bind/ES/ESGenerator.cs

@@ -27,7 +27,12 @@ namespace Bind.ES
             // so we cannot distinguish between the two.
             // Todo: add support for common and light profiles.
             Profile = "gles1";
-            // Both 1.0 and 1.1 versions
+            // no explicit version means both 1.0 and 1.1 versions
+
+            // For compatibility with OpenTK 1.0 and Xamarin, generate
+            // overloads using the "All" enum in addition to strongly-typed enums.
+            // This can be disabled by passing "-o:-keep_untyped_enums" as a cmdline parameter.
+            Settings.DefaultCompatibility |= Settings.Legacy.KeepUntypedEnums;
         }
     }
 }

Source/OpenTK/Graphics/ES11/ES11Enums.cs

@@ -57,7 +57,7 @@ namespace OpenTK.Graphics.ES11
     }
 
     /// <summary>
-    /// Used in GL.Apple.FenceSync, GL.Apple.GetInteger64 and 118 other functions
+    /// Used in GL.Apple.FenceSync, GL.Apple.GetInteger64 and 163 other functions
     /// </summary>
     public enum All : int
     {

Source/OpenTK/Graphics/ES20/ES20Enums.cs

@@ -167,7 +167,7 @@ namespace OpenTK.Graphics.ES20
     }
 
     /// <summary>
-    /// Used in GL.Amd.GetPerfMonitorCounterData, GL.Amd.GetPerfMonitorCounterInfo and 39 other functions
+    /// Used in GL.Amd.GetPerfMonitorCounterData, GL.Amd.GetPerfMonitorCounterInfo and 146 other functions
     /// </summary>
     public enum All : int
     {

Source/OpenTK/Graphics/ES30/ES30Enums.cs

@@ -385,7 +385,7 @@ namespace OpenTK.Graphics.ES30
     }
 
     /// <summary>
-    /// Used in GL.Amd.GetPerfMonitorCounterData, GL.Amd.GetPerfMonitorCounterInfo and 41 other functions
+    /// Used in GL.Amd.GetPerfMonitorCounterData, GL.Amd.GetPerfMonitorCounterInfo and 194 other functions
     /// </summary>
     public enum All : int
     {