Merge pull request #81 from ebfe/fix-build-master

Fix build with rust master
Fix deprecation warning from using .to_err_msg()
Merge pull request #82 from DaGenix/fixups

Fix deprecation warning from using .to_err_msg()
Remove cross borrowing from mut Box<T> to &mut T.

Reference: https://github.com/rust-lang/rust/pull/15171.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
Merge pull request #83 from omasanori/remove-cross-borrowing

Remove cross borrowing from mut Box<T> to &mut T.