New features:
- Windhamtab file support. Windhamtab supports pre-defined device configuration similar with /etc/crypttab. Supports `--windhamtab-pass` to only lock config under certain pass.
- user-friendly password input prompt.
- `--reauth` support under `windham AddKey`. `reauth` applies pure transform to the header instead of adding a key: suppresses warning from unauthorized revoke.
- better multi-thread unlock support. enhanced memory aware under memory pressure & `--allow-swap` support.
- minor improvements to error message and error handling.

Note:
- WINDHAM_NULL_MALLOC has been removed.
- New compile time config: DEFAULT_DISK_ENC_MEM_RATIO_CAP: controls the max capped memory for key derivation.