Resize::apply rounds the size, then the render fit the frame into that box
again: on a frame a hair under 3:2 the refit gave 1333 x 1.4999999 = 1999.49
and lost a pixel of the long edge. Frame::fit now keeps a box that already has
the frame's aspect up to rounding, and output_size rounds the native size to
whole pixels first so float noise can't decide a half-pixel tie.
Marco Arnulfo
07d7d5d498