Fix for issue #47. Use 2nd level cache for nested queries.
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/main/java/org/apache/ibatis/executor/BaseExecutor.java
	src/main/java/org/apache/ibatis/executor/CachingExecutor.java
	src/main/java/org/apache/ibatis/executor/resultset/DefaultResultSetHandler.java