Make most option functions return Option rather than OptionFunc.

This clarifies the godocs.

options.go

@@ -44,82 +44,82 @@ func (v Vars) CloneWith(vars Vars) Vars {
 }
 
 // Exit overrides the function used to terminate. This is useful for testing or interactive use.
-func Exit(exit func(int)) OptionFunc {
-	return func(k *Kong) error {
+func Exit(exit func(int)) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.Exit = exit
 		return nil
-	}
+	})
 }
 
 // NoDefaultHelp disables the default help flags.
-func NoDefaultHelp() OptionFunc {
-	return func(k *Kong) error {
+func NoDefaultHelp() Option {
+	return OptionFunc(func(k *Kong) error {
 		k.noDefaultHelp = true
 		return nil
-	}
+	})
 }
 
 // Name overrides the application name.
-func Name(name string) OptionFunc {
-	return func(k *Kong) error {
+func Name(name string) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.postBuildOptions = append(k.postBuildOptions, OptionFunc(func(k *Kong) error {
 			k.Model.Name = name
 			return nil
 		}))
 		return nil
-	}
+	})
 }
 
 // Description sets the application description.
-func Description(description string) OptionFunc {
-	return func(k *Kong) error {
+func Description(description string) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.postBuildOptions = append(k.postBuildOptions, OptionFunc(func(k *Kong) error {
 			k.Model.Help = description
 			return nil
 		}))
 		return nil
-	}
+	})
 }
 
 // TypeMapper registers a mapper to a type.
-func TypeMapper(typ reflect.Type, mapper Mapper) OptionFunc {
-	return func(k *Kong) error {
+func TypeMapper(typ reflect.Type, mapper Mapper) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.registry.RegisterType(typ, mapper)
 		return nil
-	}
+	})
 }
 
 // KindMapper registers a mapper to a kind.
-func KindMapper(kind reflect.Kind, mapper Mapper) OptionFunc {
-	return func(k *Kong) error {
+func KindMapper(kind reflect.Kind, mapper Mapper) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.registry.RegisterKind(kind, mapper)
 		return nil
-	}
+	})
 }
 
 // ValueMapper registers a mapper to a field value.
-func ValueMapper(ptr interface{}, mapper Mapper) OptionFunc {
-	return func(k *Kong) error {
+func ValueMapper(ptr interface{}, mapper Mapper) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.registry.RegisterValue(ptr, mapper)
 		return nil
-	}
+	})
 }
 
 // NamedMapper registers a mapper to a name.
-func NamedMapper(name string, mapper Mapper) OptionFunc {
-	return func(k *Kong) error {
+func NamedMapper(name string, mapper Mapper) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.registry.RegisterName(name, mapper)
 		return nil
-	}
+	})
 }
 
 // Writers overrides the default writers. Useful for testing or interactive use.
-func Writers(stdout, stderr io.Writer) OptionFunc {
-	return func(k *Kong) error {
+func Writers(stdout, stderr io.Writer) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.Stdout = stdout
 		k.Stderr = stderr
 		return nil
-	}
+	})
 }
 
 // Bind binds values for hooks and Run() function arguments.
@@ -133,61 +133,61 @@ func Writers(stdout, stderr io.Writer) OptionFunc {
 //   	AfterApply(...) error
 //
 // Called before validation/assignment, and immediately after validation/assignment, respectively.
-func Bind(args ...interface{}) OptionFunc {
-	return func(k *Kong) error {
+func Bind(args ...interface{}) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.bindings.add(args...)
 		return nil
-	}
+	})
 }
 
 // BindTo allows binding of implementations to interfaces.
 //
 // 		BindTo(impl, (*iface)(nil))
-func BindTo(impl, iface interface{}) OptionFunc {
-	return func(k *Kong) error {
+func BindTo(impl, iface interface{}) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.bindings[reflect.TypeOf(iface).Elem()] = reflect.ValueOf(impl)
 		return nil
-	}
+	})
 }
 
 // Help printer to use.
-func Help(help HelpPrinter) OptionFunc {
-	return func(k *Kong) error {
+func Help(help HelpPrinter) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.help = help
 		return nil
-	}
+	})
 }
 
 // ConfigureHelp sets the HelpOptions to use for printing help.
-func ConfigureHelp(options HelpOptions) OptionFunc {
-	return func(k *Kong) error {
+func ConfigureHelp(options HelpOptions) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.helpOptions = options
 		return nil
-	}
+	})
 }
 
 // UsageOnError configures Kong to display context-sensitive usage if FatalIfErrorf is called with an error.
-func UsageOnError() OptionFunc {
-	return func(k *Kong) error {
+func UsageOnError() Option {
+	return OptionFunc(func(k *Kong) error {
 		k.usageOnError = true
 		return nil
-	}
+	})
 }
 
 // ClearResolvers clears all existing resolvers.
-func ClearResolvers() OptionFunc {
-	return func(k *Kong) error {
+func ClearResolvers() Option {
+	return OptionFunc(func(k *Kong) error {
 		k.resolvers = nil
 		return nil
-	}
+	})
 }
 
 // Resolvers registers flag resolvers.
-func Resolvers(resolvers ...Resolver) OptionFunc {
-	return func(k *Kong) error {
+func Resolvers(resolvers ...Resolver) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.resolvers = append(k.resolvers, resolvers...)
 		return nil
-	}
+	})
 }
 
 // ConfigurationLoader is a function that builds a resolver from a file.
@@ -200,8 +200,8 @@ type ConfigurationLoader func(r io.Reader) (Resolver, error)
 // Note: The JSON function is a ConfigurationLoader.
 //
 // ~ expansion will occur on the provided paths.
-func Configuration(loader ConfigurationLoader, paths ...string) OptionFunc {
-	return func(k *Kong) error {
+func Configuration(loader ConfigurationLoader, paths ...string) Option {
+	return OptionFunc(func(k *Kong) error {
 		k.loader = loader
 		for _, path := range paths {
 			resolver, _ := k.LoadConfig(path)
@@ -210,7 +210,7 @@ func Configuration(loader ConfigurationLoader, paths ...string) OptionFunc {
 			}
 		}
 		return nil
-	}
+	})
 }
 
 // ExpandPath is a helper function to expand a relative or home-relative path to an absolute path.