Simplify sparsetable to use the new common serialization infrastructure written when adding densehashtable serialization.
Simplify sparsetable to use the new common serialization
infrastructure written when adding densehashtable serialization.

This should not (hopefully!) be user-visible; it's just cleaning up
the code somewhat, getting rid of some ugly macros, etc.

bufans/sparsehash,epitzer/sparsehash,corburn/sparsehash,aadityakalsi/sparsehash,RChehowski/sparsehash,leondutoit/sparsehash,sparsehash/sparsehash,robertschrader/sparsehash,kinjalbhavsar/sparsehash,pip010/sparsehash,pip010/sparsehash,resouer/sparsehash,bufans/sparsehash,PanHao000/sparsehash,lhigueragamboa/sparsehash,venkey-ariv/sparsehash,felixguendling/sparsehash,felixguendling/sparsehash,jacklicn/sparsehash,mikeagn/sparsehash,xinchoubiology/sparsehash,yuanjia1011/sparsehash,bufans/sparsehash,tcpan/sparsehash,fritzo/sparsehash,liuqiang2/sparsehash,gulgi/sparsehash,liuqiang2/sparsehash,lukedeo/sparsehash,kinjalbhavsar/sparsehash,zegl/sparsehash,stephane-martin/sparsehash,JanX2/sparsehash,kmammou/sparsehash,leondutoit/sparsehash,zegl/sparsehash,redknightlois/sparsehash,lhigueragamboa/sparsehash,blackball/sparsehash,felixguendling/sparsehash,guiquanz/sparsehash,pip010/sparsehash,WangDequan/sparsehash,kinjalbhavsar/sparsehash,blackball/sparsehash,xinchoubiology/sparsehash,resouer/sparsehash,lhigueragamboa/sparsehash,WangDequan/sparsehash,kmammou/sparsehash,robertschrader/sparsehash,danielwhitehall/sparsehash,tcpan/sparsehash,RChehowski/sparsehash,rob-p/sparsehash,TomasRejhons/sparsehash,venkey-ariv/sparsehash,sparsehash/sparsehash,xinchoubiology/sparsehash,redknightlois/sparsehash,JanX2/sparsehash,PanHao000/sparsehash,liuqiang2/sparsehash,WangDequan/sparsehash,blackball/sparsehash,jbboehr/sparsehash,PanHao000/sparsehash,gulgi/sparsehash,aadityakalsi/sparsehash,tgoodyear/sparsehash,jbboehr/sparsehash,lukedeo/sparsehash,JanX2/sparsehash,jacklicn/sparsehash,kaka1992/sparsehash,COMBINE-lab/sparsehash,xtao/sparsehash,guiquanz/sparsehash,zegl/sparsehash,fritzo/sparsehash,windeye/sparsehash,guiquanz/sparsehash,xtao/sparsehash,xtao/sparsehash,epitzer/sparsehash,sparsehash/sparsehash,dabbertorres/GoogleHashMaps,tgoodyear/sparsehash,yuanjia1011/sparsehash,windeye/sparsehash,danielwhitehall/sparsehash,mrxsaimon/sparsehash,aadityakalsi/sparsehash,TomasRejhons/sparsehash,borud/sparsehash,mrxsaimon/sparsehash,TomasRejhons/sparsehash,resouer/sparsehash,robertschrader/sparsehash,fritzo/sparsehash,COMBINE-lab/sparsehash,chengmo03013106/sparsehash,tgoodyear/sparsehash,kaka1992/sparsehash,tcpan/sparsehash,dabbertorres/GoogleHashMaps,rob-p/sparsehash,mrxsaimon/sparsehash,dabbertorres/GoogleHashMaps,redknightlois/sparsehash,StevenLOL/sparsehash,yuanjia1011/sparsehash,gulgi/sparsehash,danielwhitehall/sparsehash,stephane-martin/sparsehash,corburn/sparsehash,borud/sparsehash,windeye/sparsehash,corburn/sparsehash,borud/sparsehash,RChehowski/sparsehash,kaka1992/sparsehash,chengmo03013106/sparsehash,rob-p/sparsehash,kmammou/sparsehash,chengmo03013106/sparsehash,mikeagn/sparsehash,COMBINE-lab/sparsehash,StevenLOL/sparsehash,jbboehr/sparsehash,jacklicn/sparsehash,stephane-martin/sparsehash,lukedeo/sparsehash,mikeagn/sparsehash,StevenLOL/sparsehash,venkey-ariv/sparsehash,epitzer/sparsehash,leondutoit/sparsehash