[nps] correction between geocentric and geodetic ecef pos

This correction is required since jsbsim ecef is based on geocentric
model and pprz on geodetic model. This result is that lla pos computed
from ecef is wrong. It is not an issue if you use global coordinates or
if you reset the ecef ref, but it fails if only the reset is only on
altitude (NavSetAltitudeRefHere).
The correction is only computed when using flight plan init (no
JSBSIM_INIT defined in the airframe file), since the
original geodetic lla pos is required and jsbsim init xml files are
directly using geocentric pos.
Added an airframe file for the delfly.

The dual pwm submodule compiles now.

The dualpwm works, not with the pwm module on it's side, but at least one works at a time.

We now have the interuption that works, we are not yet sure if the interuption is the right one...

We now generated the dual pulses, still need to test if thoses pulses do work with the servos.

Learned that 4+18 doesn't make 20ms and cleaned a bit the code.

Cleaned the code and made it a little bit more compatible with futur changes.

Added some comments to the code.

Changed th configuration of the lisa/S in order to let it support the generation of the dualPWM. (Not yet tested).

Added some comments about how to modify this modul in order to make it more flexible.

Made the dual pulse work on the lisa S 0.1.

Made the dual servo pwm a little bit more generic.

Added the support f the dual pwm for the lisa m.