Move most API of CommandParts to util classes

Gradual transition to removing CommandParts altogether.
 - Move logic from CommandParts to utils classes

src/main/java/fr/xephi/authme/command/CommandUtils.java

@@ -1,5 +1,11 @@
 package fr.xephi.authme.command;
 
+import fr.xephi.authme.util.CollectionUtils;
+import fr.xephi.authme.util.StringUtils;
+
+import java.util.ArrayList;
+import java.util.List;
+
 public final class CommandUtils {
 
     public static int getMinNumberOfArguments(CommandDescription command) {
@@ -16,4 +22,37 @@ public final class CommandUtils {
         return command.getArguments().size();
     }
 
+    /**
+     * Provide a textual representation of a list of labels to show it as a command. For example, a list containing
+     * the items ["authme", "register", "player"] it will return "authme register player".
+     *
+     * @param labels The labels to format
+     * @return The space-separated labels
+     */
+    public static String labelsToString(Iterable<String> labels) {
+        return StringUtils.join(" ", labels);
+    }
+
+    public static double getDifference(List<String> labels1, List<String> labels2, boolean fullCompare) {
+        // Make sure the other reference is correct
+        if (labels1 == null || labels2 == null) {
+            return -1;
+        }
+
+        // Get the range to use
+        int range = Math.min(labels1.size(), labels2.size());
+
+        // Get and the difference
+        if (fullCompare) {
+            return StringUtils.getDifference(CommandUtils.labelsToString(labels1), CommandUtils.labelsToString(labels2));
+        }
+        return StringUtils.getDifference(
+            labelsToString(CollectionUtils.getRange(labels1, range - 1, 1)),
+            labelsToString(CollectionUtils.getRange(labels2, range - 1, 1)));
+    }
+
+
+
+
+
 }