Add stub for SV command

Used in Rance4 ver2.05.

src/cmd_check.c

@@ -976,6 +976,8 @@ void exec_command(void) {
 			commandST(); break;
 		case 'U':
 			commandSU(); break;
+		case 'V':
+			commandSV(); break;
 		case 'W':
 			commandSW(); break;
 		case 'X':

src/cmd_check.h

@@ -220,6 +220,7 @@ extern void commandSR();
 extern void commandSS();
 extern void commandST();
 extern void commandSU();
+extern void commandSV();
 extern void commandSW();
 extern void commandSX();
 extern void commandSI();

src/cmds.c

@@ -280,6 +280,13 @@ void commandSU() {
 	DEBUG_COMMAND("SU %d,%d:",*var1, *var2);
 }
 
+void commandSV() {
+	// Set volume (Rance4 v2.05)
+	int device = getCaliValue();
+	int volume = getCaliValue();
+	DEBUG_COMMAND_YET("SV %d,%d", device, volume);
+}
+
 void commandSQ() {
 	/* 左右別々のＰＣＭデータを合成して演奏する */
 	int noL  = getCaliValue();