modify tf idf, if a word's value is Nan change it to 0
Merge remote-tracking branch 'origin/master'

Conflicts:
	birch.txt
	birchConvergeResult.txt
	dbScan.txt
	dbScanConvergeResult.txt
	eigenV.txt
	kMeans.txt
	kMeansConvergeResult.txt
	src/filter/Filter.java
	topK.txt
	topicFileTable.txt
add empty file handling logic