Previous commit changed bincode deserializes in maildir and sqlite3.rs
from bincode::deserialize_from to using bincode::config::DefaultOptions
and bincode::Options trait's method deserialize_from.
However, these two different deserializes use a different default
settings: https://github.com/servo/bincode/issues/348
Specifically, varint encoding for integers is the default for
DefaultOptions but not when using bincode::{de,}serialize_* functions.
That means that serialized structs were not able to be deserialized.
This commit makes all {de,}serializations use the DefaultOptions
interface rather than the top level functions.
If struct memory layout changes, bincode deserialize fails with memory
allocation error of an obscene amount of bytes. Set upper limit to
deserialized bytes in each place deserialize happens.
Manos Pitsidianakis