[net2-wg] TreeRoutingEngine works

[Rodrigo Fonseca]

Hi,

I just committed a version of the TreeRoutingEngine that works, that
is, it builds trees correctly.
So far the testing was done with a dummy link estimator, since we had
little problems testing both at the same time.

Missing now is only a replacement policy for *routing* neighbors, that
is, we need to keep around a set of nodes that are the best paths to
the root. These are strictly a subset of the links kept by the
LinkEstimator.

The tests/TestTreeRouting application has a very simple test of the
code in TOSSIM.

Cheers,
Rodrigo