Make it possible to specify display of stats in a particular 'container' by separating category and container with a period.

e.g. "show stats server.network"
I failed to realize this had already been implemented without the period in the show stats command (as the command help had not been updated).
However, I would prefer the . approach as it will allow specifying multiple stats, easier wildcarding, etc.
This commit also prevents any stat from having a period in its short name.

OpenSim/Framework/Monitoring/Stats/Stat.cs

@@ -42,6 +42,8 @@ namespace OpenSim.Framework.Monitoring
     {
 //        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
 
+        public static readonly char[] DisallowedShortNameCharacters = { '.' };
+
         /// <summary>
         /// Category of this stat (e.g. cache, scene, etc).
         /// </summary>
@@ -166,6 +168,12 @@ namespace OpenSim.Framework.Monitoring
                 throw new Exception(
                     string.Format("Stat cannot be in category '{0}' since this is reserved for a subcommand", category));
 
+            foreach (char c in DisallowedShortNameCharacters)
+            {
+                if (shortName.IndexOf(c) != -1)
+                    throw new Exception(string.Format("Stat name {0} cannot contain character {1}", shortName, c));
+            }
+
             ShortName = shortName;
             Name = name;
             Description = description;