Adding gravity routine for megno (includes variational equations).
Minor optimization in variational equations
Added MEGNO helper routines
Changed misleading precompiler definition.
First step. Working for fixed timesteps.
Still issues with variable timestep.
Now working.
adding new example
Working on example
Improved structure of megno calculation in code
Minor changes to example
preparing example
removed plot
Merge branch 'hltau' into megno
added hltauscaling to test scaling relations for 3 planet systems