give networks a transmissions() method, improve Node's transmissions() method
give networks a transmissions() method, improve Node's transmissions() method

berkeley-cocosci/Wallace,Dallinger/Dallinger,Dallinger/Dallinger,berkeley-cocosci/Wallace,Dallinger/Dallinger,jcpeterson/Dallinger,jcpeterson/Dallinger,Dallinger/Dallinger,berkeley-cocosci/Wallace,jcpeterson/Dallinger,Dallinger/Dallinger,jcpeterson/Dallinger,suchow/Wallace,jcpeterson/Dallinger,suchow/Wallace,suchow/Wallace