Script-Call Safety, Environments, and better Examples!

I never expected to make this release, but just a short while after 2.16 there is now a 2.17.0! This release includes Environments, alongside a number of small bugfixes related to globals and static order initialization explosions.

• state_view::script: overloads for accepting environments and error handling functions
• sol::environment: support for sandboxing code more easily and inheriting parent environments
• sol::new_table/sol::create: for creating new tables easier without an empty state_view::create_table call.
• Improved Examples: for environments on functions and being safe while calling a script!