wip on regression trees
fixed issues with discrete variables.
added a few more fields
random forests of regression trees & an example for that.
a tiny bit of optimization in the training.
fixed up training parallelism to actually be parallel
updated the README
Merge pull request #2 from flightstats/regression_trees

Regression trees
repacking, renaming
decision tree with continuous variables implemented
converted the digits example to use the new forests
persistence for decision RandomForests, with the new capabilities; converted the OptDigitsExample to use the new forest impl.
removed test that shouldn't have worked
wine quality cast as a classification problem, rather than a regression problem.
deleted the old decision tree code
renamed the item classes to be simpler, now that there is only one type of Item
A couple of simple unit tests for the splitter.
persistence for all kinds of random forests
Merge pull request #3 from flightstats/contiuous_decision_attributes

Continuous decision attributes