Delete old constants in ShapeBasedPlacer
Delete ImageShaper.shapePrecisely() and ImageShaper.shapeSloppily(),
since ImageShaper.shape() is now fast enough. I think that passing
a PImage and a Processing color as args will be fine - WordCram is
very dependent on Processing, I don't think it'll ever be extracted.

Also delete ShapeBasedPlacer.fromImageFile(), which used those
methods. ImageShaper has a nice-enough API that we don't need it.