Are all the fields in the `RTree` struct necessary?

[asinghvi17]

None of them seem to be accessed at any point, only the index is. We could potentially make the RTree struct vastly simpler by allowing a keyword constructor + forwarding some methods to rtree.index, and doing the following:

struct RTree
	index
	ndims::Int
	lock::ReentrantLock
end

and then having a massive constructor with all keyword arguments available, as well as potentially overloading set/getproperty.
Thoughts?