sort and regroup constants
Another clean-up, following https://github.com/NebulousLabs/Sia/pull/2368#discussion_r141532311 Small tool to find out-of-order constants: https://gist.github.com/7a9a3f8fe1fff4f1e4e933baa0b34f69
Another clean-up, following https://github.com/NebulousLabs/Sia/pull/2368#discussion_r141532311 Small tool to find out-of-order constants: https://gist.github.com/7a9a3f8fe1fff4f1e4e933baa0b34f69