Replace NULL by C++11 nullptr
move optim_parameters as member of optimizer_base
Minor comment fix
Add preliminary comment
Merge branch 'master' into target_per_deme
Add some missing methods in CTable to compress further after feature selection
implement cscore_base::ignore_idxs and inherited classes

This method allows to possibly optimize evaluation if many features
are ignored (filtered out, during feature selection within moses).

It also allows to know the best possible score at the deme level
rather than globally.

For the moment on precision_bscore implements one, the other scorer
use the default empty one (i.e. doing nothing).
Some various fixes + log in *scorer::ignore_idxs
Compress ctable when feature selection within moses is use

This can greatly speed up evaluation (5x faster on a dataset with 60K
row and 1500 features, while selecting around 10 features).

Add to that it also updates the target score to stop deme search when
the best actual best candidate is found.

WARNING:

1) it relies on some horrible hack of CTable::filtered_preverse_idxs
as a result it only works for binary features

2) it also only works for precision_bscore, in order to take advantage
of that optimization you must implement ignore_idxs in your scorer.
Merge pull request #186 from ngeiswei/target_per_deme

Target per deme