Version 0.2.0

• Update dependencies (#445, #454, #456, #459, #460, #463, #465, #467)
• Use pure rust cryptography instead of libsodium (#446, #447, #449, #450, #452, #453, #455)
• Resolve dependency cycle between modules (#448)
• Use thiserror instead of unmaintained failure (#457)
• Merge tox_node and tox repositories (#466)
• Fix deadlocks (#461, #464)