Usage of libpredict

[bjorgan]

As a first step, some algorithms for finding the best pass were implemented very quickly in order to experiment with the libpredict API and get some sense on how to possibly do the calculations. Some of these calculations will be present in a future version of the libpredict API, and will probably be implemented it in a more consistent, better and more precise way. In particular do some of the tricks done in tracker.cpp seem to result in inconsistent values for AOS and LOS.

When the libpredict API becomes more stable and finished, switch to the functions contained therein and rewrite the algorithms for finding the satellite with the best pass during a given time period. Contribute to libpredict until this is achieved.