first implementation of truely readable model. use --truely_readable_model arg
var name change, check before insert
support both readable and truly_readable
map structure change and bug fix
merge master
clearer logic and bug fix
clean up one rarely used typedef
Merge pull request #135 from eHarmony/truely_readable

Truly readable model
fixed initialization bug and holdout_off required by test
Merge branch 'master' into save_best
make it work for gd