Make item lists collapsable
As a user, I want all but one item list to be collapsed so that I don't have to be scrolling endlessly until I find the item that I want.
Default behavior should be that the first item list is open while all others (from second to last) are collapsed according to the class-specific priority defined in #9 (closed) For example, a Monk would by default see the full list of PSI items (first) while INT (second), CON (third), DEX (fourth), and STR (fifth) item lists are collpased.
This user story requires to have #9 (closed) implemented first.
Non-functional requirements: N/A
Rationale: see User story