Supporting `struct` by default, would be great

[schittli]

Good evening

thanks a lot for sharing your great work!

I tried to use fluid with c# struct objects and it looks like fluid usually always expects to get class objects, for example,
TemplateOptions.Default.MemberAccessStrategy.Register<T> is declared with: where T : class

I guess, that it would be great if fluid would support structs, by default, too.

Thanks a lot, kind regards,
Thomas