aprori algorithm， easy to understand and modify




File list:
Apriori
......\Apriori.java
......\DataHandler.java
......\Interval.java
......\Item.java
......\NDI.java
......\Partition.java
......\PartitionNDI.java
......\Sampling.java
......\SamplingNDI.java
......\StopWatch.java
......\Tools.java