Updates value error messages to be consistent.

Provide both the type and value that failed conversion. Tries not to
"toString" large value types like Arrays or Maps. For those types it
will just output the type and not a value.

src/main/java/org/json/XML.java

@@ -26,7 +26,6 @@ SOFTWARE.
 
 import java.io.Reader;
 import java.io.StringReader;
-import java.lang.reflect.Method;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.util.Iterator;