Builds one node of a randomForest model tree
build_node_randomForest(tree_table, leaf_val_type, whichNode, valueNeedsTag,
dataLevels, fieldTypes = NULL)tree object
a character representing an avro type when a value is returned at a leaf node
pointer to the target node to be built
flag for whether node needs label
levels of data
type of fields
PFA as a list-of-lists that can be inserted into a cell or pool