Added (optional) time dependence.
Cleaned initialization and added kDimenWithTime
notes
VariationalMidpoint appears time-dependent capable. Need to test.
Make NonAutoLinearOscillator. RK4 stepping matches python.
fixed sign error in lagrangian
Recovered Variational Integrator of LinearOscillator
Testing for NonAutoLinearOscillator
Cleaned LD1
Tested time-dependend variational_midpoint Ld
VariationalMidpoint Working. Confirmed with python, but unittest for step needed. Fixed time evaluation bugs.