Add option to ProbABEL to list logliks in output

[lckarssen]

This is a 'liftover' of feature request #4846 from the R-forge tracker.

By default ProbABEL 0.4.0(-beta) prints \chi^2 values based on LRT (except when using mmscore, then they are based on the Wald test). It would be interesting to add the loglik and null_loglik values to the output. Since this is not useful to all, this should be enabled by a command line option.

Suggestion by Aaron I.