Allow user properties in ARS

User properties are stored in data/user/####.ini files and easily updated via JS.

This would allow sysops to add/modify settings via scripts that can later be checked via ARS.

e.g. "PROP [imsg received] count 100"

would match if the user's [imsg received] count property had the value "100". String exact comparisons would be easy (and by default, ARS string keywords are compared for "equality"), but greater/less-than could make sense for numeric properties.

Script authors would set the user properties via the userprops.js load lib.