Add larger inventory window (slots beyond hotbar)

The inventory window opened with 'E' now has 50 slots, the first row
corresponds to the hotbar, the last four rows are extra space for
storage. The inventory toolbar now only displays a subset of playerInventory.

Requires deathcap/voxel-inventory-toolbar@12600545a035627b11698c6e7828bc9d4e7d9d7a