Clean up sharding-related code
Clean up sharding-related code

Add more comments, fix style issues, etc.

potatozhao/zmap,KeelanArrendale/zmap,tdi/zmap,djeraseit/zmap,scarito/zmap-android,willscott/zmap,willscott/zmap,cicku/zmap,scarito/zmap,shakenetwork/zmap,tdi/zmap,BobuSumisu/zmap,zhuyue1314/zmap,unixfreaxjp/zmap,tdi/zmap,BobuSumisu/zmap,coolacid/zmap,unixfreaxjp/zmap,eacha/zmap,eacha/zmap,cicku/zmap,BobuSumisu/zmap,zhuyue1314/zmap,KeelanArrendale/zmap,eacha/zmap,coolacid/zmap,BobuSumisu/zmap,scarito/zmap,djeraseit/zmap,cicku/zmap,unixfreaxjp/zmap,potatozhao/zmap,shakenetwork/zmap,cicku/zmap,3L3N4/zmap,potatozhao/zmap,scarito/zmap,BobuSumisu/zmap,3L3N4/zmap,djeraseit/zmap,KeelanArrendale/zmap,potatozhao/zmap,KeelanArrendale/zmap,coolacid/zmap,scarito/zmap-android,shakenetwork/zmap,zmap/zmap,coolacid/zmap,cicku/zmap,zmap/zmap,scarito/zmap-android,willscott/zmap,scarito/zmap,tdi/zmap,3L3N4/zmap,scarito/zmap-android,scarito/zmap,potatozhao/zmap,3L3N4/zmap,djeraseit/zmap,zhuyue1314/zmap,tdi/zmap,willscott/zmap,eacha/zmap,unixfreaxjp/zmap,zmap/zmap,djeraseit/zmap,coolacid/zmap,willscott/zmap,eacha/zmap,3L3N4/zmap,zhuyue1314/zmap,shakenetwork/zmap,KeelanArrendale/zmap,shakenetwork/zmap,unixfreaxjp/zmap,zhuyue1314/zmap