Added nucleus. Better initial configuration of filaments.

mihaf

2014-03-25 fe24d29b3c8684f08dccd01f5785aa48b7137322

1
Original written by Dan Kroll in FORTRAN. Code was then largely adapted and commented by Miha Fosnaric-Fosni. Rewritten into C by Samo Penic-Peni, with help of Miha's extensive explanations.