grid.js: remove unused allEvents()
grid.js: remove unused maxKey variable
Grid: refactor row ordering into functions.
Grid: move row/column refreshes to full re-render.
Grid: recompute all maxima on re-render
Grid: fix N bugs, metric sorting, slower.

Had to kill the caching code; it's been the source of no end of bugs in
the grid for the last six months and I'm just not smart enough to fix
it. Every call goes through (slurred) render now. :(