Grid Inventory 2.1.4.3

• Fix items being ejected from a large (double) chest when placed across the seam between its two halves. A double chest reaches the block entity backstop as two independent 9x3 inventories, so an item straddling the seam looks like it overflows one half; the backstop judged the declared footprint instead of the single cell the grid actually reserves, and dropped the item on the ground.
• The stored-layout rule now lives in one place (InventoryGridState.effectiveFootprint) and both the grid rebuild and the backstop go through it, so they can no longer disagree.