Add Localization support

* Add EnglishLanguage type to store English texts
* Itemban now store English item name
* Command `/i` `/give` `/sm` `/tpnpc` can use both English and current language input

TShockAPI/Localization/EnglishLanguage.cs

@@ -0,0 +1,96 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Terraria;
+using Terraria.Localization;
+
+namespace TShockAPI.Localization
+{
+	/// <summary>
+	/// Provides a series of methods that give English texts
+	/// </summary>
+	public static class EnglishLanguage
+	{
+		private static readonly Dictionary<int, string> ItemNames = new Dictionary<int, string>();
+
+		private static readonly Dictionary<int, string> NpcNames = new Dictionary<int, string>();
+
+		private static readonly Dictionary<int, string> Prefixs = new Dictionary<int, string>();
+
+		internal static void Initialize()
+		{
+			var culture = Language.ActiveCulture;
+
+			var skip = culture == GameCulture.English;
+
+			try
+			{
+				if(!skip)
+					LanguageManager.Instance.SetLanguage(GameCulture.English);
+
+				for (var i = -48; i < Main.maxItemTypes; i++)
+				{
+					ItemNames.Add(i, Lang.GetItemNameValue(i));
+				}
+
+				for (var i = -17; i < Main.maxNPCTypes; i++)
+				{
+					NpcNames.Add(i, Lang.GetNPCNameValue(i));
+				}
+
+				foreach (var field in typeof(Main).Assembly.GetType("Terraria.ID.PrefixID")
+							.GetFields().Where(f => !f.Name.Equals("Count", StringComparison.Ordinal)))
+				{
+					Prefixs.Add((int) field.GetValue(null), field.Name);
+				}
+			}
+			finally
+			{
+				if(!skip)
+					LanguageManager.Instance.SetLanguage(culture);
+			}
+		}
+
+		/// <summary>
+		/// Get the english name of an item
+		/// </summary>
+		/// <param name="id">Id of the item</param>
+		/// <returns>Item name in English</returns>
+		public static string GetItemNameById(int id)
+		{
+			string itemName;
+			if (ItemNames.TryGetValue(id, out itemName))
+				return itemName;
+
+			return string.Empty;
+		}
+
+		/// <summary>
+		/// Get the english name of a npc
+		/// </summary>
+		/// <param name="id">Id of the npc</param>
+		/// <returns>Npc name in English</returns>
+		public static string GetNpcNameById(int id)
+		{
+			string npcName;
+			if (NpcNames.TryGetValue(id, out npcName))
+				return npcName;
+
+			return string.Empty;
+		}
+
+		/// <summary>
+		/// Get prefix in English
+		/// </summary>
+		/// <param name="id">Prefix Id</param>
+		/// <returns>Prefix in English</returns>
+		public static string GetPrefixById(int id)
+		{
+			string prefix;
+			if (Prefixs.TryGetValue(id, out prefix))
+				return prefix;
+
+			return string.Empty;
+		}
+	}
+}