Support different button-door relation in Lab Recruits random EFSM generator

[deid00]

The current random generator supports the n-m relation between doors and buttons, namely, a door can be opened by many buttons and a button can open many doors. We would like to give the user the possibility of selecting other relations:

• 1-1 relation: a door is opened by a button and a button opens at most one door
• n-1 relation: a door can be opened by many buttons but a button opens at most one door
• 1-n relation: a door is opened by a button and a button opens many doors