title: Edit trees within an H2O GBM
body: <p>I would like to do some kind of &quot;custom GBM&quot; with the H2O format, so it can be exported in MOJO.
  In particular, I would like to edit trees (by changing the split rules and the leafs predictions).</p>
  <p>I don't see anything providing access to the H2OGradientBoostingEstimator trees, and even less possibilities to modify them.
  Do you know if it is it possible to do that ? (or would it require to basically re-write the h2o.estimators.gbm package...)</p>
  <p>Many thanks !</p>