Add experimental DynamicTextureModule.ReuseTextures flag, currently only configurable on compile.

Disabled (status quo) by default.
This flag makes the dynamic texture module reuse cache previously dynamically generated textures given the same input commands and extra params for 24 hours.
This occurs as long as those commands would always generate the same texture (e.g. they do not contain commands to fetch data from the web).
This makes texture changing faster as a viewer-cached texture uuid is sent and may reduce simulator load in regions with generation of lots of dynamic textures.
A downside is that this stops expiry of old temporary dynamic textures from the cache,
Another downside is that a jpeg2000 generation that partially failed is currently not regenerated until restart or after 24 hours.

OpenSim/Region/CoreModules/Scripting/LoadImageURL/LoadImageURLModule.cs

@@ -67,6 +67,12 @@ namespace OpenSim.Region.CoreModules.Scripting.LoadImageURL
             return true;
         }
 
+//        public bool AlwaysIdenticalConversion(string bodyData, string extraParams)
+//        {
+//            // We don't support conversion of body data.
+//            return false;
+//        }
+
         public byte[] ConvertUrl(string url, string extraParams)
         {
             return null;
@@ -236,9 +242,11 @@ namespace OpenSim.Region.CoreModules.Scripting.LoadImageURL
                     stream.Close();
                 }
             }
+
             m_log.DebugFormat("[LOADIMAGEURLMODULE] Returning {0} bytes of image data for request {1}",
                                        imageJ2000.Length, state.RequestID);
-            m_textureManager.ReturnData(state.RequestID, imageJ2000);
+
+            m_textureManager.ReturnData(state.RequestID, imageJ2000, false);
         }
 
         #region Nested type: RequestState