Added a module that generate dual pwm pulses.

Documentation associated to that module : https://wiki.paparazziuav.org/wiki/Module/Dual_pwm


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.