Implement clear confirmation (#1623)

Introduces:
- `clearinventoryconfirmtoggle` command with shorter aliases
- `confirmClear` boolean in UserData

Essentials/src/com/earth2me/essentials/User.java

@@ -61,6 +61,7 @@ public class User extends UserData implements Comparable<User>, IMessageRecipien
     private String afkMessage;
     private long afkSince;
     private Map<User, BigDecimal> confirmingPayments = new WeakHashMap<>();
+    private String confirmingClearCommand;
     private long lastNotifiedAboutMailsMs;
 
     public User(final Player base, final IEssentials ess) {
@@ -846,6 +847,14 @@ public class User extends UserData implements Comparable<User>, IMessageRecipien
         return confirmingPayments;
     }
 
+    public String getConfirmingClearCommand() {
+        return confirmingClearCommand;
+    }
+    
+    public void setConfirmingClearCommand(String command) {
+        this.confirmingClearCommand = command;
+    }
+
     /**
      * Returns the {@link ItemStack} in the main hand or off-hand. If the main hand is empty then the offhand item is returned - also nullable.
      */