Shorter trapezoid sides for source_grid_oblique

Update source-grid trapezoid corners + height (flatter)

textvqa patch tiles: switch to camera image; ROI + SINK + attention figures (PNG)

32B full results: nips.tex (Vanilla/SD-RPN/GroundFlow), trainer_state for run2 + SD-RPN, textvqa patch tile figures (PNG), eval/sync scripts