improved grid x layout to match warp grid, align on 1/2 grid spacing
improved grid x layout to match warp grid, align on 1/2 grid spacing

radiasoft/sirepo,radiasoft/sirepo,radiasoft/sirepo,mkeilman/sirepo,mrakitin/sirepo,mrakitin/sirepo,mkeilman/sirepo,mrakitin/sirepo,radiasoft/sirepo,mkeilman/sirepo,radiasoft/sirepo,mkeilman/sirepo,mrakitin/sirepo