Scrap should use consistant grid size

[vpicaver]

When morphing the scrap, the grid is inconsistent and statically set based on size of sketch scale. We might want to let user set this grid size. For scraps that have small scale 1:250 or smaller, we should use a finer grid size than large scale scraps. But maybe fix the max grid size to 1m x 1m or something like that.