added lvl1 controller interface (+ template for buffer swapping)
added lvl0 controller interfaces
added controlmodes namespace + default control modes
all data units now are splitted into an interface (this has to be implemented) and a ptrprovider (this is a conveniene class. it stores pointer and implements the interface. if all data is already somewhere in ram, you can set the pointers of this class and have a working data unit)

added listener relay classes

See merge request !22

the xml file can be edited with on draw.io

they pass all data they receive to configurable callbacks

Change to show error if the current value remains static over a period of time

See merge request !21

Previously the error only appears if the current value remains zero over a period of time.

Adapts PIDController to virtual time

Adapts PIDController to virtual time

See merge request !20