Interface MrubyFile

A `trait` useful for organising Rust types into dynamic mruby files. # Examples ``` # use mrusty::Mruby; # use mrusty::MrubyFile; # use mrusty::MrubyImpl; # use mrusty::MrubyType; struct Cont { value: i32 } impl MrubyFile for Cont { fn require(mruby: MrubyType) { mruby.def_class_for:: ("Container"); } } let mruby = Mruby::new(); mruby.def_file:: ("cont"); ```