Add minimum-pay-amount setting to limit how little you can /pay someone.

Add 'minimumPayAmount' translatable message.
Create NumberUtil#displayCurrencyExactly(BigDecimal, IEssentials).

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

@@ -229,4 +229,6 @@ public interface ISettings extends IConf {
     boolean isDropItemsIfFull();
     
     boolean isLastMessageReplyRecipient();
+    
+    BigDecimal getMinimumPayAmount();
 }

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

@@ -1121,4 +1121,8 @@ public class Settings implements net.ess3.api.ISettings {
     @Override public boolean isLastMessageReplyRecipient() {
         return config.getBoolean("last-message-reply-recipient", false);
     }
+
+    @Override public BigDecimal getMinimumPayAmount() {
+        return new BigDecimal(config.getString("minimum-pay-amount", "0.001"));
+    }
 }

Essentials/src/com/earth2me/essentials/commands/Commandpay.java

@@ -4,6 +4,8 @@ import com.earth2me.essentials.ChargeException;
 import com.earth2me.essentials.CommandSource;
 import com.earth2me.essentials.Trade;
 import com.earth2me.essentials.User;
+import com.earth2me.essentials.utils.NumberUtil;
+
 import net.ess3.api.MaxMoneyException;
 import org.bukkit.Server;
 
@@ -32,6 +34,9 @@ public class Commandpay extends EssentialsLoopCommand {
         }
 
         amount = new BigDecimal(stringAmount);
+        if (amount.compareTo(ess.getSettings().getMinimumPayAmount()) < 0) { // Check if amount is less than minimum-pay-amount
+            throw new Exception(tl("minimumPayAmount", NumberUtil.displayCurrencyExactly(ess.getSettings().getMinimumPayAmount(), ess)));
+        }
         loopOnlinePlayers(server, user.getSource(), false, user.isAuthorized("essentials.pay.multiple"), args[0], args);
     }
 

Essentials/src/com/earth2me/essentials/utils/NumberUtil.java

@@ -37,6 +37,10 @@ public class NumberUtil {
         return tl("currency", ess.getSettings().getCurrencySymbol(), formatAsCurrency(value));
     }
 
+    public static String displayCurrencyExactly(final BigDecimal value, final IEssentials ess) {
+        return tl("currency", ess.getSettings().getCurrencySymbol(), value.toPlainString());
+    }
+
     public static boolean isInt(final String sInt) {
         try {
             Integer.parseInt(sInt);

Essentials/src/config.yml

@@ -536,6 +536,9 @@ economy-log-enabled: false
 # Default is false. 
 use-bukkit-permissions: false
 
+# Minimum acceptable amount to be used in /pay.
+minimum-pay-amount: 0.001
+
 ############################################################
 # +------------------------------------------------------+ #
 # |                   EssentialsHelp                     | #

Essentials/src/messages.properties

@@ -570,3 +570,4 @@ msgDisabledFor=\u00a76Receiving messages \u00a7cdisabled \u00a76for \u00a7c{0}\u
 msgEnabled=\u00a76Receiving messages \u00a7cenabled\u00a76.
 msgEnabledFor=\u00a76Receiving messages \u00a7cenabled \u00a76for \u00a7c{0}\u00a76.
 msgIgnore=\u00a7c{0} \u00a74has messages disabled.
+minimumPayAmount=\u00a7cThe minimum amount you can pay is {0}.