Add ability to set admin password at startup

The -a flag has been added to allow specifying a new admin password on
the command line.  This password will only be used for the current
session and will not be written to the configuration file.  If the
password contains spaces, wrap it in quotes on the command line.  The
quotes should be omitted with the /auth command.

Eg, starting the server with:
    ./MovieNight -a "the admin password"
the auth command in chat would be:
    /auth the admin password

main.go

@@ -18,6 +18,7 @@ var (
 	addr       string
 	sKey       string
 	stats      = newStreamStats()
+	sAdminPass string
 )
 
 func setupSettings() error {
@@ -30,6 +31,11 @@ func setupSettings() error {
 		return fmt.Errorf("Missing stream key is settings.json")
 	}
 
+	if sAdminPass != "" {
+		fmt.Println("Password provided at runtime; ignoring password in set in settings.")
+		settings.AdminPassword = sAdminPass
+	}
+
 	sstore = sessions.NewCookieStore([]byte(settings.SessionKey))
 	sstore.Options = &sessions.Options{
 		Path:     "/",
@@ -43,6 +49,7 @@ func setupSettings() error {
 func main() {
 	flag.StringVar(&addr, "l", "", "host:port of the MovieNight")
 	flag.StringVar(&sKey, "k", "", "Stream key, to protect your stream")
+	flag.StringVar(&sAdminPass, "a", "", "Set admin password.  Overrides configuration in settings.json.  This will not write the password to settings.json.")
 	flag.BoolVar(&pullEmotes, "e", false, "Pull emotes")
 	flag.Parse()
 

settings.go

@@ -27,6 +27,7 @@ type Settings struct {
 	MaxMessageCount int
 	TitleLength     int // maximum length of the title that can be set with the /playing
 	AdminPassword   string
+	RegenAdminPass  bool // regenerate admin password on start?
 	StreamKey       string
 	ListenAddress   string
 	ApprovedEmotes  []string // list of channels that have been approved for emote use.  Global emotes are always "approved".
@@ -90,9 +91,11 @@ func LoadSettings(filename string) (*Settings, error) {
 		return s, fmt.Errorf("value for MaxMessageCount must be greater than 0, given %d", s.MaxMessageCount)
 	}
 
-	s.AdminPassword, err = generatePass(time.Now().Unix())
-	if err != nil {
-		return nil, fmt.Errorf("unable to generate admin password: %s", err)
+	if s.RegenAdminPass == true || s.AdminPassword == "" {
+		s.AdminPassword, err = generatePass(time.Now().Unix())
+		if err != nil {
+			return nil, fmt.Errorf("unable to generate admin password: %s", err)
+		}
 	}
 
 	if s.RateLimitChat == -1 {

settings_example.json

@@ -2,6 +2,7 @@
 	"MaxMessageCount": 300,
 	"TitleLength": 50,
 	"AdminPassword": "",
+	"RegenAdminPass": true,
 	"Bans": [],
 	"StreamKey": "ALongStreamKey",
 	"ListenAddress": ":8089",