Added NONE as an option in BufferStorageFlags

None is a desirable option in this enum because it's used much like
BufferUsageHint.StaticDraw for ARB_Buffer_Storage. Using it explicitly
in user code is more clear than 0, and makes it more clear to the
inexperienced author that none is an option.

Source/Bind/Specifications/GL2/overrides.xml

@@ -2911,6 +2911,7 @@
       <token name="BUFFER_MAP_POINTER" value="0x88BD" />
     </enum>
     <enum name="BufferStorageFlags">
+      <use enum="VERSION_1_1" token="NONE" />
       <use enum="VERSION_3_0" token="MAP_READ_BIT" />
       <use enum="VERSION_3_0" token="MAP_WRITE_BIT" />
       <use enum="VERSION_4_4" token="CLIENT_STORAGE_BIT" />

Source/OpenTK/Graphics/OpenGL/GLEnums.cs

@@ -29585,6 +29585,10 @@ namespace OpenTK.Graphics.OpenGL
     /// </summary>
     public enum BufferStorageFlags : int
     {
+        /// <summary>
+        /// Original was GL_NONE = 0
+        /// </summary>
+        None = ((int)0),
         /// <summary>
         /// Original was GL_MAP_READ_BIT = 0x0001
         /// </summary>

Source/OpenTK/Graphics/OpenGL4/GL4Enums.cs

@@ -15632,6 +15632,10 @@ namespace OpenTK.Graphics.OpenGL4
     /// </summary>
     public enum BufferStorageFlags : int
     {
+        /// <summary>
+        /// Original was GL_NONE = 0
+        /// </summary>
+        None = ((int)0),
         /// <summary>
         /// Original was GL_MAP_READ_BIT = 0x0001
         /// </summary>