Dependencies of the thorn

For integration of geodesics in the numerical spacetime, this thorn requires thorn PUGHInterp.

For integration of geodesics in the analytical spacetime, this thorn requires thorn Exact.

For calculating the curvature invariants I and J in the numerical spacetime this thorn additionally requires thorn PsiKadelia. (Zorro?).

For data streaming TimeGeodesic requires CactusNet/NetGeometry which requires external/RemoteIO and external/TCPXX which I've not been able to re-plug this time ([Francisco, 08.05.2002]). Thorn ifdef's are used so that it can be compiled without these, disabling the data streaming.