Breaking changes

The extended attribute names are now encrypted on macOS in the same way as Linux. This breaks compatibility with securefs < 2.0 if the platform is macOS.
- This removes many ugly workarounds on macOS and improves privacy.
- If the extended attributes are important to you, please export them and import later. A tool is provided here.

New features

New command unmount and ismount are added.
Background mounting (mount -b) is rewritten, such that
- Background mounting is now supported on Windows (by creating a child process in an invisible console)
- The foreground process will wait until either the child process mounts successfully or exits. The foreground process will exit with 0 for the former case and non-zero for the latter. The callers no longer need to read the logs to distinguish success from failure.
Long name suffixes on lite format are now tunable. The default is changed from ... to .ll to improve Windows compatibility.
- Existing repos can be migrated with migrate-long-name command. Windows users are encouraged to do so if the repo is in lite format.
New option --max-idle-seconds will cause automatically unmount if the filesystem doesn't receive any requests for the given duration.