Set options from defaults on first start

Data/GenericData.dat specifies what the default values for some options
should be. Respect them on startup if the options in config are unset.

internal/config/config.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 
@@ -37,8 +38,9 @@ type Options struct {
 type Config struct {
 	filename string `toml:"-"`
 
-	Ordoor  `toml:"ordoor"`
-	Options `toml:"options"`
+	Defaults *Options `toml:"-"`
+	Ordoor   `toml:"ordoor"`
+	Options  `toml:"options"`
 }
 
 func Load(filename string) (*Config, error) {
@@ -54,6 +56,12 @@ func Load(filename string) (*Config, error) {
 	return &out, err
 }
 
+func (c *Config) HasUnsetOptions() bool {
+	var empty Options
+
+	return c.Options == empty
+}
+
 func (c *Config) Save() error {
 	f, err := os.OpenFile(c.filename, os.O_WRONLY, 0644)
 	if err != nil {
@@ -69,6 +77,16 @@ func (c *Config) DataFile(path string) string {
 	return filepath.Join(c.DataDir, path)
 }
 
+func (c *Config) ResetDefaults() error {
+	if c.Defaults == nil {
+		return errors.New("Defaults not available")
+	}
+
+	c.Options = *c.Defaults
+
+	return c.Save()
+}
+
 func (o *Options) ResolutionIndex() int {
 	if o.XRes == 640 && o.YRes == 480 {
 		return 1