Fix calculation of log likelihoods for BaumWelch learning

- Removed unused variable oldLogLikelihood
- remove re-initialization of newLogLikelihood to -Inf,
    which caused only the last sequence in a set of sequences
    to be used in the fitness calculation!
Merge pull request #48 from madmaxreach/development

Fix calculation of log likelihoods for BaumWelch learning algorithm.