Return NULL pointers to indicate non-existent elements/nodes,
Return NULL pointers to indicate non-existent elements/nodes,

Use consistent IDs when refining mesh in serial



git-svn-id: e88a1e38e13faf406e05cc89eca8dd613216f6c4@2457 434f946d-2f3d-0410-ba4c-cb9f52fb0dbf

vikramvgarg/libmesh,dmcdougall/libmesh,vikramvgarg/libmesh,svallaghe/libmesh,pbauman/libmesh,aeslaughter/libmesh,giorgiobornia/libmesh,90jrong/libmesh,balborian/libmesh,balborian/libmesh,coreymbryant/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,dmcdougall/libmesh,dknez/libmesh,libMesh/libmesh,benkirk/libmesh,balborian/libmesh,coreymbryant/libmesh,vikramvgarg/libmesh,friedmud/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,pbauman/libmesh,aeslaughter/libmesh,aeslaughter/libmesh,vikramvgarg/libmesh,aeslaughter/libmesh,balborian/libmesh,BalticPinguin/libmesh,90jrong/libmesh,benkirk/libmesh,vikramvgarg/libmesh,benkirk/libmesh,cahaynes/libmesh,BalticPinguin/libmesh,dmcdougall/libmesh,pbauman/libmesh,dschwen/libmesh,balborian/libmesh,roystgnr/libmesh,libMesh/libmesh,benkirk/libmesh,svallaghe/libmesh,hrittich/libmesh,jwpeterson/libmesh,vikramvgarg/libmesh,aeslaughter/libmesh,friedmud/libmesh,svallaghe/libmesh,friedmud/libmesh,cahaynes/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,jwpeterson/libmesh,benkirk/libmesh,capitalaslash/libmesh,hrittich/libmesh,dknez/libmesh,giorgiobornia/libmesh,benkirk/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,pbauman/libmesh,aeslaughter/libmesh,benkirk/libmesh,svallaghe/libmesh,balborian/libmesh,90jrong/libmesh,cahaynes/libmesh,dschwen/libmesh,giorgiobornia/libmesh,dschwen/libmesh,capitalaslash/libmesh,dschwen/libmesh,vikramvgarg/libmesh,aeslaughter/libmesh,capitalaslash/libmesh,pbauman/libmesh,dknez/libmesh,vikramvgarg/libmesh,roystgnr/libmesh,hrittich/libmesh,dschwen/libmesh,pbauman/libmesh,friedmud/libmesh,dknez/libmesh,balborian/libmesh,benkirk/libmesh,vikramvgarg/libmesh,pbauman/libmesh,benkirk/libmesh,pbauman/libmesh,libMesh/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,dschwen/libmesh,hrittich/libmesh,balborian/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,hrittich/libmesh,cahaynes/libmesh,friedmud/libmesh,dknez/libmesh,coreymbryant/libmesh,cahaynes/libmesh,dknez/libmesh,libMesh/libmesh,aeslaughter/libmesh,dschwen/libmesh,coreymbryant/libmesh,aeslaughter/libmesh,svallaghe/libmesh,roystgnr/libmesh,dmcdougall/libmesh,90jrong/libmesh,hrittich/libmesh,roystgnr/libmesh,capitalaslash/libmesh,hrittich/libmesh,friedmud/libmesh,coreymbryant/libmesh,libMesh/libmesh,dmcdougall/libmesh,90jrong/libmesh,balborian/libmesh,BalticPinguin/libmesh,libMesh/libmesh,balborian/libmesh,coreymbryant/libmesh,cahaynes/libmesh,dmcdougall/libmesh,capitalaslash/libmesh,dmcdougall/libmesh,friedmud/libmesh,jwpeterson/libmesh,hrittich/libmesh,capitalaslash/libmesh,coreymbryant/libmesh,dschwen/libmesh,svallaghe/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,friedmud/libmesh,coreymbryant/libmesh,cahaynes/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,pbauman/libmesh,friedmud/libmesh,dknez/libmesh,svallaghe/libmesh,dknez/libmesh,roystgnr/libmesh,90jrong/libmesh,hrittich/libmesh,svallaghe/libmesh,jwpeterson/libmesh,90jrong/libmesh,cahaynes/libmesh,svallaghe/libmesh,libMesh/libmesh,libMesh/libmesh,dmcdougall/libmesh,90jrong/libmesh,giorgiobornia/libmesh,BalticPinguin/libmesh,90jrong/libmesh,capitalaslash/libmesh