Merge pull request #1 from samuelharden/new-lm

New lm
Fix comment typos
Reword comment to be clearer
Simplify the 4 constructor forms to 2
Merge pull request #2 from samuelharden/new-lm

remove Redundant comment after smoothing
Avoid calculating log if we would then clamp it to 0
Merge pull request #3 from samuelharden/new-lm

Removed passing unique term to get_sumextra since no weighting scheme is ...(instead passing 0)
adding the changes of 4 to 2 constructor
Merge branch 'UnigramLMWeight' into new-lm
Removing unecessary constructor from LMWeight