Merge branch 'gravity_multi_dt' into 'master'
Gravity multi dt Some improvements to the gravity code: - Corrected typo in 4th order vector powers. - Use a user-defined opening angle for the distance checks. - Increase accuracy of the exact gravity calculation. - Only do exact gravity calculation if a matching result file is not present in the same directory. - Reinstate the dumping of individual task timers. - Added script to plot the accuracy of the calculation. - Crash if the M2L kernel is called with a length smaller than the softening length. See merge request !331