Derive Macro frunk::LabelledGeneric

#[derive(LabelledGeneric)]

Derives a Generic instance based on Field + HList for a given Struct (Tuple Structs not supported because they have no labels)

There may be problems if your field names contain certain characters. This can be solved by adding letters to the create_enums_for! macro invocation in frunk_core::labelled via a PR :)