Switching to shallow copy makes checking for empty dict unnecessary (<2% change in time) so we can simplify code again. What do you think of the change in docs?  When we settle on graph.py I'll do multi and di versions.
Switching to shallow copy makes checking for empty dict
unnecessary (<2% change in time) so we can simplify code again.
What do you think of the change in docs?  When we settle on graph.py
I'll do multi and di versions.

Addresses #314

--HG--
extra : convert_revision : svn%3A3ed01bd8-26fb-0310-9e4c-ca1a4053419f/networkx/trunk%401529

dmoliveira/networkx,dhimmel/networkx,nathania/networkx,ionanrozenfeld/networkx,blublud/networkx,blublud/networkx,bzero/networkx,RMKD/networkx,aureooms/networkx,jtorrents/networkx,chrisnatali/networkx,jakevdp/networkx,kernc/networkx,harlowja/networkx,nathania/networkx,kai5263499/networkx,jtorrents/networkx,blublud/networkx,debsankha/networkx,harlowja/networkx,nathania/networkx,jni/networkx,michaelpacer/networkx,dmoliveira/networkx,sharifulgeo/networkx,jfinkels/networkx,farhaanbukhsh/networkx,dhimmel/networkx,OrkoHunter/networkx,Sixshaman/networkx,RMKD/networkx,ghdk/networkx,sharifulgeo/networkx,dhimmel/networkx,ionanrozenfeld/networkx,sharifulgeo/networkx,farhaanbukhsh/networkx,bzero/networkx,jcurbelo/networkx,kai5263499/networkx,kernc/networkx,beni55/networkx,chrisnatali/networkx,jakevdp/networkx,RMKD/networkx,debsankha/networkx,jni/networkx,chrisnatali/networkx,jakevdp/networkx,tmilicic/networkx,goulu/networkx,JamesClough/networkx,cmtm/networkx,aureooms/networkx,yashu-seth/networkx,kernc/networkx,aureooms/networkx,jni/networkx,SanketDG/networkx,wasade/networkx,harlowja/networkx,ghdk/networkx,dmoliveira/networkx,andnovar/networkx,debsankha/networkx,ghdk/networkx,ionanrozenfeld/networkx,NvanAdrichem/networkx,farhaanbukhsh/networkx,bzero/networkx,kai5263499/networkx,ltiao/networkx