big changes to get-des-obsinfo for new destest tables
add TILE=0 to query
add 2 static lines to output; supress positions w/nobs<2
update get-des-lightcurves for y2 tables

snforce table works, snobs table untested, probably doesn't work.
add dbname option to get-des-lightcurves
clean up get-des-obsinfo (remove y1 stuff)