HW4: Calculate the probability of a tag given the previous tag
	def ProbPrecedingTag(trainData,posDic):

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: <BUG-FIX> in CalculatePi() we count tag appearances at the beginning of a sentence
	if the sentence length is 0:
	memory access violation when trying to access the first word

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: <BUG-FIX> in ParseTrainingFile()
	splitting to sentences using the char '.'
	the token e.g. was splitted into 2 sentences.
	now splitting using the '.\t'

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: minor name change

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: Calculate the probability of a token: given it's tag
	def WordLikelihoodProbabilities(trainData,tokenDic,posDic):

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: minor change name
HW4: <BUG-FIX> in CalculatePi()
	init all the tags that never starts a sentence

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: implement viterby algorithm

Signed-off-by: unknown <zkk12345@gmail.com>
HW4: minor changes