HW2: tTestAnalysis return tokensFreqs instead of 'DONE'
HW2: Pest Collocations_CountedDictionary and tokensFreqs from tTestAnalysis() to PmiAnalysis()
HW2: <BUG-FIX> in tTestAnalysis()
takes the 100 smallest pmi scores instead of highest
HW2: <BUG-FIX> tokensFreqs is not consistent with collocationsFreqs that was created after .lower()
	use .lower() before creating tokensFreqs
HW2: Close input files, cahnge writing format
HW2: Output the top 100 PMI scores into PMI_raw.txt file
Output the exactly 20 appearances with their PMI score into PMI_select.txt file

Signed-off-by: unknown <zkk12345@gmail.com>
HW2: change filw writing format
HW2: <BUG-FIX> sort the collocations with exactly 20 appearances inPmiAnalysis()
HW2: <BUG-FIX> sort the collocations with exactly 20 appearances in tTestAnalysis

Signed-off-by: unknown <zkk12345@gmail.com>
HW2: <BUG-FIX> when calc the raw frequancy score
	devide by tokens number instead of  collocations number
HW2: reorganize the functions

Signed-off-by: unknown <zkk12345@gmail.com>
HW2: minor variables minor changes (variables names)

Signed-off-by: unknown <zkk12345@gmail.com>
HW2: minor changes
Fixed the TScore Formula