[shortcuts] add support for items

[Traelblaser]

Add support for items to the shortcuts addon
Supersedes and Closes #2076

Some test cases:
/drieddate1 will eat a dried date +1
/drieddate will eat a dried date
/drieddate+1 will eat a dried date +1
other food should work as above, though I did not test every single food. Food with +2 or +3 might be interesting to test, but I didn't have any.

/fire5 still works (regression in the inherited code)
most other spells already worked
/warp still functions with e.g. selindrile's warp command
/remedy eats a remedy
/instant warp will eat an instant warp scoll
/instant reraise will eat an instane reraise
Dispensable items aren't supported by this e.g. REMA guns, other stuff like that.