First version of eval-candidate

That tool allows to associate a weight of a bunch of candidates
indicating their likelihood of solving a problem. This code could be
used for model combination for weighting different models before
voting.
Add default empty ignore features in load{I}Table{_optimized}
Minor indentiation fix
Add more options to eval-candidates (in particular simple version for prerec, using just precision)
Changed formula in the case of prerec (using 1/2 instead of 1 for unknown)
Merge branch 'master' into eval_candidates
Merge pull request #132 from ngeiswei/eval_candidates

Eval candidates