main: pull regular exits into main function

The replaces the "does not return" comments with
an explicit os.Exit, which is unambigous.

info.go

@@ -41,5 +41,4 @@ func info(filename string) {
 	s := cf.ScryptObject
 	fmt.Printf("ScryptObject: Salt=%dB N=%d R=%d P=%d KeyLen=%d\n",
 		len(s.Salt), s.N, s.R, s.P, s.KeyLen)
-	os.Exit(0)
 }

init_dir.go

@@ -79,5 +79,4 @@ func initDir(args *argContainer) {
 	}
 	tlog.Info.Printf(tlog.ColorGrey+"You can now mount it using: %s%s %s MOUNTPOINT"+tlog.ColorReset,
 		tlog.ProgramName, mountArgs, friendlyPath)
-	os.Exit(0)
 }

main.go

@@ -103,7 +103,6 @@ func changePassword(args *argContainer) {
 		os.Exit(exitcodes.WriteConf)
 	}
 	tlog.Info.Printf(tlog.ColorGreen + "Password changed." + tlog.ColorReset)
-	os.Exit(0)
 }
 
 // printVersion prints a version string like this:
@@ -257,23 +256,26 @@ func main() {
 			tlog.Fatal.Printf("Usage: %s -info CIPHERDIR", tlog.ProgramName)
 			os.Exit(exitcodes.Usage)
 		}
-		info(args.config) // does not return
+		info(args.config)
+		os.Exit(0)
 	}
 	// "-init"
 	if args.init {
 		if flagSet.NArg() > 1 {
 			tlog.Fatal.Printf("Usage: %s -init [OPTIONS] CIPHERDIR", tlog.ProgramName)
 			os.Exit(exitcodes.Usage)
 		}
-		initDir(&args) // does not return
+		initDir(&args)
+		os.Exit(0)
 	}
 	// "-passwd"
 	if args.passwd {
 		if flagSet.NArg() > 1 {
 			tlog.Fatal.Printf("Usage: %s -passwd [OPTIONS] CIPHERDIR", tlog.ProgramName)
 			os.Exit(exitcodes.Usage)
 		}
-		changePassword(&args) // does not return
+		changePassword(&args)
+		os.Exit(0)
 	}
 	// Default operation: mount.
 	if flagSet.NArg() != 2 {