[fprint] Cleaning up questions

[Daniel Drake]

Bastien Nocera wrote:
> Just a quick question. When an enrollment, or a verification gets
> started, is it finished when the status signal tells us it's finished,
> or do the "Stop" variants only cancel those operations if they're not
> finished? (In which case we might want to rename the calls to "Cancel"
> instead).

You have to stop it after receiving the result. But it can also be used 
for cancellation. The async API could do with some rework.

> Also, does closing the device stop any enrollment/verification?

No, but it should.

Daniel