Segmentation fault when trying to invoke the keyboard shortcut help

[tmadlener]

The changes in #11 broke the display of the keyboard shortcut help leading to a segmentation fault when trying to toggle them.

This was originally reported in key4hep/key4hep-spack#603

The problem is this loop here (at least that is what gdb claims):

CED/src/server/glced.cc

Lines 601 to 610 in cc537ca

	for(i=NUMBER_DATA_LAYER;i<NUMBER_DETECTOR_LAYER+NUMBER_DATA_LAYER;i++){
	snprintf(label,MAX_STR_LEN+1, "(%s) [%c] %s%i: %s", isLayerVisible(i)?"X":"_",detec_layer_keys[-1*NUMBER_DATA_LAYER+i], ((i)<10)?"0":"", (i), layerDescription[i]);
	if(strlen(label) >= MAX_STR_LEN){
	label[MAX_STR_LEN-3]='.';
	label[MAX_STR_LEN-2]='.';
	label[MAX_STR_LEN-1]='.';
	label[MAX_STR_LEN]=0;
	}
	shortcuts.push_back(label);
	}