Handles

# Changelog

* Sub-Systems functions !

- getSubSystems() : get an array of string corresponding to the systems

- getSubSystemHealth(string): get a float 0 to 1 of the current health of the system (0 if system not found)

- getSubSystemStatus(string): get a boolean of the current status of the system (false if system not found)

- setSubSystemStatus(string, boolean): set the current status of a system (return a boolean depending if the subsystem was found)

* I have slightly improved some code in existant methods, nothing should have changed, but let me know if it's the case