additions and improvements to ThreadLocalStringBuilder

Mage/src/mage/util/ThreadLocalStringBuilder.java

@@ -0,0 +1,27 @@
+package mage.util;
+
+/**
+ *
+ * @author BetaSteward
+ */
+public class ThreadLocalStringBuilder extends ThreadLocal<StringBuilder> {
+
+    private int size;
+    
+    public ThreadLocalStringBuilder(int size) {
+        this.size = size;
+    }
+    
+    @Override
+    protected StringBuilder initialValue() {
+        return new StringBuilder(size);
+    }
+
+    @Override
+    public StringBuilder get() {
+        StringBuilder b = super.get();
+        b.setLength(0); // clear/reset the buffer
+        return b;
+    }
+    
+}