Improved performance of topological_sort and topological_sort_recursive.
Improved performance of topological_sort and topological_sort_recursive.

topological_sort
   - Replaced list.insert with list.append
   - Replaced dict with set

topological_sort_recursive
   - Replaced list.insert with list.append
   - Replaced a linear search with a constant time search.

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