set_heart_beat - turn the heart beat calling on/off in current object
void set_heart_beat(int onflag)
This function turns on and off automatic calls every 2 seconds to
the lfun heart_beat. If 'onflag' is 0 then calls is turned off,
otherwise calling is turned on.
- NOTA BENE
heart_beats are costly. Use them only if neccessary. Especially
do not use them for 'down counters' such as counting down the
life time of a torch, use call_out for such purposes.
- SEE ALSO
If there is a runtime error in your heart_beat routine calling
of the heart_beat will be automatically turned off.