v0.2.0

Release Highlights

• Allow Thread to be forcibly reset to a stopped state.
• Improve the Table API, add functions that skip IntoValue conversion and
  simplify Table::next.
• Support __newindex.
• Auto conversion improvements, add a Variadic wrapper type to indicate
  variadic multi-values instead of bare arrays.
• Add Function::compose and Function::bind for easier generic function
  handling from Rust.
• Completely track used memory within interpreter instances. Tracks both
  gc-arena allocated Gc pointers as well as all normal heap allocations
  using gc-arena external allocation tracking.
• Fuel system to limit the execution time of Lua code.
• Properly handle ... in table constructors.
• Implement table.select('#'), table.pack, and table.unpack.
• Fix local function declarations to be visible in their own function body.
• Guard against arbitrary recursion depth of callbacks (only ever a risk for
  Threads calling callbacks on other Threads, aka Lua coroutines).