Added /undo and /redo as aliases.

plugin.yml

@@ -81,9 +81,11 @@ commands:
     /redo:
         description: Redoes the last action (from history)
         usage: /<command> [times]
+        aliases: ['redo']
     /undo:
         description: Undoes the last action
         usage: /<command> [times]
+        aliases: ['undo']
     unstuck:
         description: Escape from being stuck inside a block
         usage: /<command> 

src/com/sk89q/worldedit/commands/HistoryCommands.java

@@ -31,7 +31,7 @@ import com.sk89q.worldedit.*;
  */
 public class HistoryCommands {
     @Command(
-        aliases = {"/undo"},
+        aliases = {"/undo", "undo"},
         usage = "[times]",
         desc = "Undoes the last action",
         min = 0,
@@ -57,7 +57,7 @@ public class HistoryCommands {
     }
     
     @Command(
-        aliases = {"/redo"},
+        aliases = {"/redo", "redo"},
         usage = "[times]",
         desc = "Redoes the last action (from history)",
         min = 0,