Variant internal layout and ctti::type_id_t

[Manu343726]

There are some redditors complaining about fixed storage of ctti::detail::string (The type that stores type names at compile-time as part of ctti::type_id_t). This actually affects cpp::Variant too since it uses too much space for the usual type names we have in a variant (int, char, Entity, etc. ctti::detail::string length is 256 by default IIRC).

See comments here: https://www.reddit.com/r/programming/comments/3we1fy/getting_the_type_of_a_template_argument_as_string/?ref=share&ref_source=link