Inventory Refactor

With progressive commits instead of a full blown rewrite this time.
I intend to close #598 and get our inventory code readable and easy to modify.
Will also close #1486 .

Changes made:
Switch to using the new inventory graphic
Index inventory pages by name
Simplify page switching
Remove redundant animation states
Rename animation grids
Refactor `closed`, `opened`, `craftingClosed`, and `craftingOpened` into `animUpdate`
Refactor `keypressed`
Refactor `nextAvailableSlot`
Refactor `craft` into `craftCurrentSlot`
Add drop item functionality
Finish `drop` function (adds node for all non-projectiles)
Fixes crafting with a full materials page
Clean up comments
Make the inventory text slightly smaller
Add sounds for full inventory and drop
Fix loading to work with scrolls