Note: I am not sure about return value. Currently I return "did I delete
sth flag", alternatively one could return deleted record, or even croak
if record was not there.
Attempt to improve performance.
Previous implementation happened to be very slow (on my laptop it took 5
minutes to read small pwsafe file and save it back). I profiled the code
and it turned out, this cost was totally dominated by the
Crypt::PWSafe3::random function (which on every call accesses system
random seed).
I replaced it with Bytes::Random::Secure which seeds using OS crypto but
afterwards uses embedded generator. Performance improvement is drastical,
the same read&save takes about half a second on the same laptop.
