Implement server side named parameters

[luc65r]

No description provided.

[tomusdrw]

Awesome stuff!! Looks great, thanks!

[luc65r]

Oh I just found out it doesn't work with the meta argument

[tomusdrw]

Good point, didn't think of that. Can we add a test for this? I guess the solution would be to either:

1. Attempt to detect the meta argument (either based on the type or the variable name)
2. Require an extra attribute/variant to skip the first parameter.

[luc65r]

I fixed it, I hope I didn't change too much code.

Now it has some issues with attributes (see commented out code in tests/macros.rs). Attributes can be in an other pr.

[tomusdrw]

Suggested change

	let param_types: Vec<_> = fn_args.iter().cloned().map(|arg| *arg.ty).collect();
	let arg_names: Vec<_> = fn_args.iter().cloned().map(|arg| *arg.pat).collect();
	let param_types = fn_args.iter().map(|arg| *arg.ty).collect::<Vec<_>>();
	let arg_names = fn_args.iter().map(|arg| *arg.pat).collect::<Vec<_>>();

My preference would be to add a generic parameter to collect, but I'm not super strong on this.

Also .cloned() doesn't seem required if we dereference/copy the type, is it?

[luc65r]

syn::Type and syn::Pat don't implement Copy, so there must be a .clone() somewhere.
It should be more efficient to clone only syn::Type or syn::Pat instead of the whole syn::FnArg.