change storage type of alias dictionary to be IReadOnlyDictionary

src/Discord.Net.Commands/CommandService.cs

@@ -32,7 +32,7 @@ namespace Discord.Commands
         internal readonly RunMode _defaultRunMode;
         internal readonly Logger _cmdLogger;
         internal readonly LogManager _logManager;
-        internal readonly Dictionary<char, char> _quotationMarkAliasMap;
+        internal readonly IReadOnlyDictionary<char, char> _quotationMarkAliasMap;
 
         public IEnumerable<ModuleInfo> Modules => _moduleDefs.Select(x => x);
         public IEnumerable<CommandInfo> Commands => _moduleDefs.SelectMany(x => x.Commands);

src/Discord.Net.Commands/CommandServiceConfig.cs

@@ -19,7 +19,7 @@ namespace Discord.Commands
 
         /// <summary> Collection of aliases that can wrap strings for command parsing. 
         /// represents the opening quotation mark and the value is the corresponding closing mark.</summary>
-        public Dictionary<char, char> QuotationMarkAliasMap { get; set; }
+        public IReadOnlyDictionary<char, char> QuotationMarkAliasMap { get; set; }
         = new Dictionary<char, char>()
         {
             {'\"', '\"' },

src/Discord.Net.Commands/Info/CommandInfo.cs

@@ -20,7 +20,7 @@ namespace Discord.Commands
 
         private readonly CommandService _commandService;
         private readonly Func<ICommandContext, object[], IServiceProvider, CommandInfo, Task> _action;
-        internal readonly Dictionary<char,char> _quotationAliases;
+        internal readonly IReadOnlyDictionary<char,char> _quotationAliases;
 
         public ModuleInfo Module { get; }
         public string Name { get; }