Implement the options menu, part 1

This commit implements loading and saving options from/to config, and
enough UI toolkit magic to allow changes to boolean options to be
persisted.

We now respect the "play movies" setting and take screen resolution
from the config file.

internal/config/config.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"os"
 	"path/filepath"
 
 	"github.com/BurntSushi/toml"
@@ -11,8 +12,32 @@ type Ordoor struct {
 	VideoPlayer []string `toml:"video_player"`
 }
 
+// Things set
+type Options struct {
+	PlayMovies   bool `toml:"play_movies"`
+	Animations   bool `toml:"animations"`
+	PlayMusic    bool `toml:"play_music"`
+	CombatVoices bool `toml:"combat_voices"`
+	ShowGrid     bool `toml:"show_grid"`
+	ShowPaths    bool `toml:"show_paths"`
+	PointSaving  bool `toml:"point_saving"`
+	AutoCutLevel bool `toml:"auto_cut_level"`
+
+	XRes int `toml:"x_resolution"`
+	YRes int `toml:"y_resolution"`
+
+	MusicVolume int `toml:"music_volume"`
+	SFXVolume   int `toml:"sfx_volume"`
+
+	UnitSpeed int `toml:"unit_speed"`
+	AnimSpeed int `toml:"animation_speed"`
+}
+
 type Config struct {
-	Ordoor `toml:"ordoor"`
+	filename string `toml:"-"`
+
+	Ordoor  `toml:"ordoor"`
+	Options `toml:"options"`
 }
 
 func Load(filename string) (*Config, error) {
@@ -23,9 +48,21 @@ func Load(filename string) (*Config, error) {
 		return nil, err
 	}
 
+	out.filename = filename
+
 	return &out, err
 }
 
+func (c *Config) Save() error {
+	f, err := os.OpenFile(c.filename, os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return toml.NewEncoder(f).Encode(c)
+}
+
 // TODO: case-insensitive lookup
 func (c *Config) DataFile(path string) string {
 	return filepath.Join(c.DataDir, path)