Merge branch 'master' of git://github.com/JohnLangford/vowpal_wabbit
first implementation of truely readable model. use --truely_readable_model arg
var name change, check before insert
support both readable and truly_readable
1st impl of --mask
option name and description change
map structure change and bug fix
fix little bug
--feature_mask using weight vector to save mask
var name modified and cleaning
--holdout arg to use examples for test only
printout change and cleaning
modify printout for holdout
add h to the end of each line
resolve merge issue
Merge pull request #136 from eHarmony/mask

--feature_mask_on
minor wording tweak
more general holdout_valid
bug fix
--save_best_model based on holdout loss