Sia v1.2.0

This is a minor release that incorporates major changes to the host and wallet modules. The host's storage backend has been completely rewritten to improve performance and scalability. Admin privileges are also no longer required to be a host on Windows. The wallet has (finally!) moved to an on-disk database, meaning that it will unlock instantly after the database is synced to the blockchain. The wallet also now supports creating a new wallet from an existing seed, and "sweeping" the coins in an existing seed into another wallet. Finally, addressing a frequent need of new users, the wallet can be recreated with a new seed, meaning users no longer have to manually delete their wallet folder.

NOTE: Upgrading an existing host can take quite a long time. Please be patient. Similarly, the first time you unlock the new wallet, it will take a long time because it's initializing the database. This only needs to occur once.

This release marks a huge uptick in the number of contributors to Sia! 🎉
The following people contributed to v1.2.0:

• @RNabel added bash completions for siac and a command that lists contract details. Power users will definitely appreciate this!
• @GlenDC documented the gateway RPC protocol and started tackling numerous gateway issues. Look out for him in the next release!
• @VoidingWarranties fixed a gateway bug. Couldn't stay away, huh? :)
• @S-anasol cleaned up some host code.
• @poiuty updated our Go dependency in the readme.

If you want to contribute to Sia, drop by our Slack. It's a big project and we can always use more help!