integrateNDt et adjointNDt: in terms of nDt

instead of tInt (float).  The integer division
will introduces a roundup that could result in
adjoint incompatibility.
Rewritten TLM integration as proper 'operator'

We define the operator launcher containing all
the information (the same for the direct and
adjoint operator); parameters, reference
trajectory, tInt and t0.

The operator itself can then be applied (as
direct or adjoint) on different perturbations
through integrate() and adjoint() method (which
now only take the perturbation as argument.
Modification to kdvLauncher __init__

More 'operator' oriented.
Modified Trajectory in consequences.
Also, I made sure the real integration time is
greater than the argument passed to the
constructor (real time is a multiple od dt)
Modified kdvSVLauncher in accordance
small typo
...found the (puny) error... adjoint ok

4 hours for so small an error!