Merge remote-tracking branch 'luca/depth-criterion-rf' into depth_stop
Fix default parameters for RF depth stop criteria.
Minor changes to RF depth and size stopping.
Add support for loading random forests from hdf5 files given by their id.
Fix loading random forests from an hdf5 file into an existing object.
Allow passing random seeds to RandomForest::learn and friends from Python.
Use the HDF5File class to write HDF5 files in writeHDF5().
Use the HDF5File class to read HDF5 files in readHDF5().