v0.0.7

• Fix a number of issues in support for async tasks (#50, #51, #52, #54)
• Improve error messages when using Shuttle primitives outside a Shuttle test (#42)
• Add support for thread local storage (the thread_local! macro) (#43, #53)
• Add support for Once cells (#49)
• Simplify some dependencies to improve build times (#55)
• Move context_switches and my_clock functions into a new current module (#56)