Feature request: Short lived password cache

[ozzi-]

I have 3 volumes I mount all at once (via mount favorites). They share the same password, therefore I use the "Cache passwords and keyfiles in memory" checkbox, otherwise I would have to repeat the password 3 times.

What do you think of adding an option, that caches the password only during mouting the favorites and clears it after a few seconds?

Thanks for the great work!