Warn if node or inventory item can't be found
Check if consumables exist before adding

Fix #1685
Merge branch 'master' of github.com:hawkthorne/hawkthorne-journey into fix_unknown_nodes

Conflicts:
	src/items/item.lua
Merge pull request #1684 from hawkthorne/fix_unknown_nodes

Warn if node or inventory item can't be found