Add PriorityAttribute and sortby priority in Search

src/Discord.Net.Commands/Attributes/PriorityAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace Discord.Commands
+{
+    /// <summary> Sets priority of commands </summary>
+    [AttributeUsage(AttributeTargets.Method)]
+    public class PriorityAttribute : Attribute
+    {
+        /// <summary> The priority which has been set for the command </summary>
+        public int Priority { get; }
+
+        /// <summary> Creates a new <see cref="PriorityAttribute"/> with the given priority. </summary>
+        public PriorityAttribute(int priority)
+        {
+            Priority = priority;
+        }
+    }
+}

src/Discord.Net.Commands/Command.cs

@@ -24,6 +24,7 @@ namespace Discord.Commands
         public string Summary { get; }
         public string Remarks { get; }
         public string Text { get; }
+        public int Priority { get; }
         public bool HasVarArgs { get; }
         public IReadOnlyList<string> Aliases { get; }
         public IReadOnlyList<CommandParameter> Parameters { get; }
@@ -70,6 +71,9 @@ namespace Discord.Commands
                 if (remarksAttr != null)
                     Remarks = remarksAttr.Text;
 
+                var priorityAttr = source.GetCustomAttribute<PriorityAttribute>();
+                Priority = priorityAttr?.Priority ?? 0;
+
                 Parameters = BuildParameters(source);
                 HasVarArgs = Parameters.Count > 0 ? Parameters[Parameters.Count - 1].IsMultiple : false;
                 Preconditions = BuildPreconditions(source);

src/Discord.Net.Commands/CommandService.cs

@@ -180,7 +180,7 @@ namespace Discord.Commands
         public SearchResult Search(IUserMessage message, string input)
         {
             string lowerInput = input.ToLowerInvariant();
-            var matches = _map.GetCommands(input).ToImmutableArray();
+            var matches = _map.GetCommands(input).OrderByDescending(x => x.Priority).ToImmutableArray();
             
             if (matches.Length > 0)
                 return SearchResult.FromSuccess(input, matches);