train-draw: refactor dataset loading and delay subdir creation
train-draw: refactor dataset loading and delay subdir creation

drewlinsley/draw_classify,mohammadpz/draw,langholz/draw,negar-rostamzadeh/draw,ablavatski/draw,drewlinsley/draw_classify,dribnet/draw,drewlinsley/draw_classify,jbornschein/draw