Add possibility to go to PEP 0

[Benhalor]

I do it

[jabby]

What is the goal of set a PEEP below alarm threshold?

[Benhalor]

The min peep setting is now 5 cmH2O. It should be 0 cm H2O, because some medical cases require this kind of peep

[jabby]

Ok I understand. How alarms should work for this kind of settings?

See the following alarms:

• https://github.com/makers-for-life/makair-firmware/blob/master/srcs/alarm_controller.cpp#L34-L39
• https://github.com/makers-for-life/makair-firmware/blob/master/srcs/alarm_controller.cpp#L54-L59
• https://github.com/makers-for-life/makair-firmware/blob/master/srcs/alarm_controller.cpp#L104-L109

[Benhalor]

@Benhalor should ask the regulatory team if the feature is still mandatory. And how to deal with the alarms issue pointed out by @jabby