Procedural macro attribute to match structure types with an enum variant.
This macro can be applied on a module to make a connection between each defined struct and a newly created enum type. This enum is built into the same module as the macro is invocated upon. The macro will also implement valuefromtype_traits::FromType on the enum for each struct (within the module) as generic argument.
See the documentation or [valuefromtype_macros/src/lib.rs] for usage example(s).