add and use IdRef::non_nil() instead of doing deref'd comparisons against nil
add and use IdRef::non_nil() instead of doing deref'd comparisons against nil

aepsil0n/glutin,Jayflux/glutin,Ms2ger/glutin,nox/glutin,TimNN/glutin,vvuk/glutin,adambadawy/glutin,ozkriff/glutin,tomaka/winit,mvdnes/glutin,bvssvni/glutin,paulrouget/glutin,mneumann/glutin,kornholi/glutin,glennw/glutin,vberger/glutin,tomaka/glutin,nc4rrillo/glutin,notriddle/glutin,tempbottle/glutin,robertknight/glutin,mmatyas/glutin,servo/glutin,larsbergstrom/glutin,mitchmindtree/glutin,mbrubeck/glutin,fkaa/glutin,mbrubeck/glutin,ecoal95/glutin,retep998/glutin,christopheraugustus/glutin