Returns true if the `i'th tree (0-offset) is rooted, false otherwise.
- true if the tree is thought to be rooted (could be rooted because this is NCL's default, or it could indicate that a [&R] comment was encountered. i should be in the range [0, ntrees)
Assumes that `i' will be in the range [0..ntrees).
Definition at line 805 of file nxstreesblock.cpp.