SCOTLAND — Deep in the polling doldrums, Scottish Labour has a plot to sneak into power regardless.  Once the favorite to topple a tired Scottish National Party that’s run Scotland’s devolved government for almost two decades, Scottish Labour now polls in either a distant second or third place in most projections. A fifth-consecutive SNP victory seems inevitable at nationwide elections on May 7. Yet officials across the parties now whisper in private that polls could be overstating the SNP’s