University-of-Reading-Space-Science/HUXt: Minor bug fix and examples update

This version includes a small but important bug fix to HUXt.solve(). When running HUXt in the sidereal frame, CME longitudes were incorrectly adjusted. The required adjustment is proportional to the CME launch time, and so this error grew linearly with increasing CME launch times. It was practically negligible for CME launch times within a day of model initialisation, but could result in significant errors in the CME longitude if the launch time was several days after the model initialisation. Adjusted longitudes are now a separate parameter tracked through in the ConeCME objects.