Pointer now holds itempile
Dropping on an existing pile picks up that pile (swap with held)
Consolidate dropSlot/pickUpSlot to clickSlot; same logic for both (swap w/ cursor)
null -> undefined
Replace CSS scale transform with larger elements
Try to use nearest-neighbor interpolation for pixelization > fuzzy edges

From https://developer.mozilla.org/en-US/docs/Web/CSS/image-rendering?redirectlocale=en-US&redirectslug=CSS%2Fimage-rendering#Examples
Doesn't seem to have an effect on Chrome or Safari(?)
Firefox requires argument to document.createTextNode()
Get clientX in MouseEvent for Firefox
Pickup item pile nodes at center, instead of top-left corner
Right-click drops one
Minor cleanup
Merge piles on drop
Swap when merging fails
Add right-click pickup = pick up half a pile

Requires deathcap/itempile@5aaf01e9e1e0f75e62413237338757c88fd40223
Add right-click drop = only drop one, now with working merging
Handle splitting to zero = no item to hold
Clear on split leftover zero (same as full pickup)