now are usable as functions for userdata.
allows free functions and lambdas to provide useful operations, like operator+*-/
and other things which may not be implemented as class members.
Refactoring on function_types.hpp performed to slim down some of the calls: could use more refactoring
Drastically simplified userdata's binding capabilities: constructor supports both `:` and `.` syntax (but member functions DO NOT).
All tests are passing
Added pop() function to `reference`
`stack.hpp` now has many more functions to properly handle user data
`types.hpp` now has `userdata_t` and `lightuserdata_t` to faciliate `stack`'s `pop` and `push` operations
Class binding functionality built into `table` and `state`, as well as placed in `userdata` class in `userdata.hpp`
demangling detail now present for clang, gcc, and MSVC (somewhat for MSVC)
Constructor arity still needs to be handled for `userdata<T>`
tests updated and passing
But! I left it on the `sol::function` type, because it's necessary to discard returns. The .call is still there, though, just incase you need it. <3
reverse_indices_builder is also there, to make sure we can push and pop without the lua api taking our types and breaking them for the std::tuple returns.
All is at it should be~
It'll be up to @Rapptz's to make further changes to make sure GCC compiles, but the core of the functionality is there and my work is essentially done.
Class bindings are up next, but really I don't want to even touch those. :c
