[PROPOSAL] Fallback if extension not in PASSWORD_STORE_EXTENSIONS_DIR.

[Greg Minshall]

Karl,

> Many programs behave the other way: an extension can be installed in a
> user-specific location or in a system location or both, and the
> user-specific location always shadows the system location.

i don't know if this was the original thinking, but i think because this
is a security program, one wants to be extra careful that the user
doesn't (too (*)) inadvertently turns on
possibly risky features.

cheers, Greg

(*) there are never guarantees.