improve exception documentation
improve state_view default handlers
add SAFE_PROPAGATION defines for compiling C++ as Lua
add examples for automatic operator registrations and as_container
fix tutorial code
change tests to not throw unless absolutely necessary
provide synchronization for file writing in tests
provide thread safety around thread tests for REQUIRE
add ostream automatic support
change 5.1 compat to only kick in luaL_loadbufferx and luaL_loadfilex when LuaJIT is version 2.0.1 and lower
fix how `stack_aligned_protected_function` and its friends behave
add new internal handler details to allow for stack-based handlers with maximum performance
update `string_shim` typedef to simply be called `string_view` and use `string_view` in all public-facing APIs.
