v0.7.0

• Remove Cobalt's threaded coroutine system. All functions are capable of unwinding and restoring their state, so it is no longer needed.
• Remove DebugHandler. One may now either use debug hooks (which are now inherited across coroutines) or add an InterruptHandler instead.
• Many changes to the stdlib to bring it more in line with Lua 5.4.
• Add a new test system, which can be run against both Cobalt and other Lua implementations, to ensure better compliance.