Listen for and refresh on 'changed' event from inventory
Try to only update node image if changed, to fix flickering
Cache full URL to fix flashing on setting ../../items relative path (comparison failed)
Use inventory.set() instead of direct array access so changed events are properly sent

Requires deathcap/inventory@84d43eaf5dff5c6b344da869ec32a6c011456b7c
Update for inventory slot -> get API change

Requires deathcap/inventory@dc0633c729107af4485388a7da232e50f0782bdd
Use inventory get() accessor instead of direct array access
Set z-index so held item is rendered on top
Fix inventory not updating when picking/placing to split/merge
Detect dragging an item with mouse button held for drag-paint
Add 'drag painting' -- hold right-click, drag over item slots to distribute

Allows filling many slots with one of an item, quickly. Cuts down on tedious
clicking. Currently only supports holding right-click not left-click (as it
only drops one item on mouseover).