wallet2: minor cleanup
wallet2: minor cleanup

- use std::vector::std::deque to not leak when exceptions happen
- use std::unique_ptr instead of the deprecated std::auto_ptr

eiabea/bitmonero,ranok/bitmonero,ranok/bitmonero,ranok/bitmonero,ranok/bitmonero,eiabea/bitmonero,eiabea/bitmonero,eiabea/bitmonero,ranok/bitmonero,ranok/bitmonero,eiabea/bitmonero,eiabea/bitmonero