Add a field asset_flags and a corresponding enum to the asset database. This

CHANGES THE ASSET SERVER PROTOCOL and means you CAN NOT MIX PRIOR VERSIONS
WITH LATER ONES. It may also eat your babies, yada, yada, yada.
The usual cautions for migrations to the assets table apply.
Coding: Can not guarantee nut free.

OpenSim/Framework/AssetBase.cs

@@ -33,6 +33,15 @@ using OpenMetaverse;
 
 namespace OpenSim.Framework
 {
+    [Flags]
+    public enum AssetFlags : int
+    {
+        Normal = 0,
+        Maptile = 1,
+        Rewritable = 2,
+        Collectable = 4
+    }
+
     /// <summary>
     /// Asset class.   All Assets are reference by this class or a class derived from this class
     /// </summary>
@@ -206,6 +215,12 @@ namespace OpenSim.Framework
             set { m_metadata.Temporary = value; }
         }
 
+        public AssetFlags Flags
+        {
+            get { return m_metadata.Flags; }
+            set { m_metadata.Flags = value; }
+        }
+
         [XmlIgnore]
         public AssetMetadata Metadata
         {
@@ -233,6 +248,7 @@ namespace OpenSim.Framework
         private bool m_local;
         private bool m_temporary;
         private string m_creatorid;
+        private AssetFlags m_flags;
 
         public UUID FullID
         {
@@ -330,5 +346,11 @@ namespace OpenSim.Framework
             get { return m_creatorid; }
             set { m_creatorid = value; }
         }
+
+        public AssetFlags Flags
+        {
+            get { return m_flags; }
+            set { m_flags = value; }
+        }
     }
 }