Recursive routine to find all actual (eligible) leave nodes in the
local partition for a given treeID.
Alternatively use tem_findPath, which uses precomputed paths in the tree
and should speed up the search (at the expense of storing the paths
TreeID to find in the array of Elements
Candidate childs, which might be considered as neighbors
Nodes of different colours represent the following:
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.