Rename class_utility to create_class.
Split function.hpp.
Fix ltypeid for tables.
Split builtin_types from converters.
Make converted_function's ctor non-explicit.
Move raw_function to builtin_types.
Fix clang's warnings.
Add g++ warning options.
Fix most of gcc's warnings.
Fix casting function* <-> void*.
Fix function pointer retrieval.

Bugs surfaced on MSVC where apparently sizeof(memfunc*) <= sizeof(void*).
light_function_traits was overly complicated.

Use an integral constant is_light_function instead.