Target management change

[nhochberger]

Each nucleus is suppossed to contain at least one nucleolus. The largest nucleolus is the desired target. Other nucleoli are not to be written to the targets-file. If no nucleolus can be found in a certain nucleus, the center of that nucleus is to be written to the targets-file. Targets of empty nuclei has to be separated by an accordant comment in the targets-file:

#nucleoli
1 : [123, 456]
2 : [12, 45]
3 : [23, 56]
#empty nuclei
4 : [12, 256]
5 : [13, 45]