Bug/api fixes to randomizer:
Class internal variable is unique, which means it is shared by all threads using API -> bad bad.
Definition of rand_r calls for int *, not int.
Added variable 'range' to randomize, so user can define the range from where the random number is generated.
Ferry can now be boarded from both points (L and D).
Disable stdout buffering (eclipse gdb console is buffered by default).
Protect the state of genthread by mutex.