Implemented the GL part of ARB_framebuffer_sRGB (issue [#587])

Source/Bind/Specifications/GL2/enumext.spec

@@ -687,7 +687,7 @@ passthru: /* Reuse tokens from ARB_framebuffer_object */
 #	use ARB_framebuffer_object	    FRAMEBUFFER_INCOMPLETE_MULTISAMPLE
 #	use ARB_framebuffer_object	    MAX_SAMPLES
 passthru: /* Reuse tokens from ARB_framebuffer_sRGB */
-	use ARB_framebuffer_sRGB	    FRAMEBUFFER_SRGB
+#	use ARB_framebuffer_sRGB	    FRAMEBUFFER_SRGB
 passthru: /* Reuse tokens from ARB_half_float_vertex */
 	use ARB_half_float_vertex	    HALF_FLOAT
 passthru: /* Reuse tokens from ARB_map_buffer_range */
@@ -6389,6 +6389,12 @@ GetTextureParameter enum:
 PixelType enum:
 	use ARB_depth_buffer_float	    FLOAT_32_UNSIGNED_INT_24_8_REV
 
+# Promoted from ARB_framebuffer_sRGB
+EnableCap enum:
+	use ARB_framebuffer_sRGB	    FRAMEBUFFER_SRGB
+
+GetPName enum:	
+	use ARB_framebuffer_sRGB	    FRAMEBUFFER_SRGB
 
 
 # End (don't remove, or the last token may be missed!)

Source/OpenTK/Graphics/GL/GLEnums.cs

@@ -392,6 +392,7 @@ namespace OpenTK.Graphics
         VertexProgramPointSize = ((int)0X8642),
         VertexProgramTwoSide = ((int)0X8643),
         PointSprite = ((int)0X8861),
+        FramebufferSrgb = ((int)0X8Db9),
     }
 
     public enum ErrorCode
@@ -1050,6 +1051,7 @@ namespace OpenTK.Graphics
         MaxColorAttachments = ((int)0X8cdf),
         MaxColorAttachmentsExt = ((int)0X8cdf),
         MaxSamples = ((int)0X8D57),
+        FramebufferSrgb = ((int)0X8Db9),
     }
 
     public enum GetTextureParameter
@@ -6387,7 +6389,6 @@ namespace OpenTK.Graphics
         SeparateAttribs = ((int)0X8c8d),
         TransformFeedbackBuffer = ((int)0X8c8e),
         TransformFeedbackBufferBinding = ((int)0X8c8f),
-        FramebufferSrgb = ((int)0X8Db9),
         SamplerCubeShadow = ((int)0X8dc5),
         UnsignedIntVec2 = ((int)0X8dc6),
         UnsignedIntVec3 = ((int)0X8dc7),