MapperMethodInvoker should be set to public

[brucelwl]

MapperMethodInvoke should be set to public, I used this interface in my custom extension for mybatis

mybatis-3/src/main/java/org/apache/ibatis/binding/MapperProxy.java

Lines 95 to 99 in 02308d3

	interface MapperMethodInvoker {
	Object invoke(Object proxy, Method method, Object[] args, SqlSession sqlSession) throws Throwable;
	}

code

public interface MapperMethodInvoker { 
   Object invoke(Object proxy, Method method, Object[] args, SqlSession sqlSession) throws Throwable; 
 } 

[harawata]

Fixed via #3415