added a compiler flag to allow calculating TC/IC scores as described in the following paper:

L. Salichos, A. Stamatakis, A. Rokas:
"Novel Information Theory-Based Measures for Quantifying Incongruence among Phylogenetic Trees".
In Molecular Biology and Evolution, 2014.

By default RAxML computes TC/IC scores a bit differently, please read the RAxML manual for further details.