Cleaned up class_
Removed old workarounds, added proper static_assert and std::integral_constant.
Removed unused duplicate pointee.hpp
Added a pointee specialisation for value types
Removed boost::mpl and boost::type_traits from class_metadata
Implemented value_arg as alias template
Removed boost::mpl and boost::type_traits from data_members
Removed old workarounds from extract
Removed boost::mpl, boost::type_traits and old workarounds from arg converters
Cleaned up args/keywords
Removed boost::mpl from make_function and make_constructor