Migrate from boost to std where possible

[thinlang]

There are a number of boost classes which can now be migrated over to the standard.

• boost::bind -> std::bind or lambdas
• boost::reference_wrapper -> std::reference_wrapper
• boost::any -> std::any
• boost::equality_comparable and other concepts could be moved to their std equivalent
• The various boost::mpl::xxx have the potential to be migrated to similar constructs in std
• boost::remove_reference/remove_const/is_reference/etc... type traits could be migrated to their std equivalent
• boost::is_pod/is_integral/etc... have std equivalents
• boost::enable_if and other similar metaprogramming templates could be moved to their std equivalents
• boost::begin/end/prev/next have equivalents in std
• boost::iteratorxxx types/helpers could be investigated to see if they can be replaced with std or range-based for loops
• boost::mem_fn -> std::mem_fn
• boost::size -> std::size
• boost::range related types and helpers could have equivalents in the standard based on the situation
• boost::posix_time could potentially be migrated to std::chrono
• boost::filesystem -> std::filesystem