Added a clock freeze option (/sim/freeze/clock). This can be specified

via the command line (--enable-clock-freeze / --disable-clock-freeze)
and can be toggled during a run.  However this property is not currently
bound to any menu or keystroke so you have to do it via the gui property
interface or externally via the web property browser or a script.

src/Main/main.cxx

@@ -999,6 +999,8 @@ static void fgMainLoop( void ) {
 	= fgGetNode("/position/latitude-deg");
     static const SGPropertyNode *altitude
 	= fgGetNode("/position/altitude-ft");
+    static const SGPropertyNode *clock_freeze
+	= fgGetNode("/sim/freeze/clock", true);
     static const SGPropertyNode *cur_time_override
 	= fgGetNode("/sim/time/cur-time-override", true);
 
@@ -1077,10 +1079,32 @@ static void fgMainLoop( void ) {
     // cout << "Warp = " << globals->get_warp() << endl;
 
     // update "time"
-    if ( globals->get_warp_delta() != 0 ) {
+    static bool last_clock_freeze = false;
-	globals->inc_warp( globals->get_warp_delta() );
+
+    if ( clock_freeze->getBoolValue() ) {
+	// clock freeze requested
+	if ( cur_time_override->getLongValue() == 0 ) {
+	    fgSetLong( "/sim/time/cur-time-override",
+		       t->get_cur_time() + globals->get_warp() );
+	    globals->set_warp( 0 );
+	}
+    } else {
+	// no clock freeze requested
+	if ( last_clock_freeze == true ) {
+	    // clock just unfroze, let's set warp as the difference
+	    // between frozen time and current time so we don't get a
+	    // time jump (and corresponding sky object and lighting
+	    // jump.)
+	    globals->set_warp( cur_time_override->getLongValue() - time(NULL) );
+	    fgSetLong( "/sim/time/cur-time-override", 0 );
+	}
+	if ( globals->get_warp_delta() != 0 ) {
+	    globals->inc_warp( globals->get_warp_delta() );
+	}
     }
 
+    last_clock_freeze = clock_freeze->getBoolValue();
+
     t->update( longitude->getDoubleValue() * SGD_DEGREES_TO_RADIANS,
 	       latitude->getDoubleValue() * SGD_DEGREES_TO_RADIANS,
 	       cur_time_override->getLongValue(),

src/Main/options.cxx

@@ -192,7 +192,7 @@ fgSetDefaults ()
                                 // Freeze options
     fgSetBool("/sim/freeze/master", false);
     fgSetBool("/sim/freeze/position", false);
-    fgSetBool("/sim/freeze/time-of-day", false);
+    fgSetBool("/sim/freeze/clock", false);
     fgSetBool("/sim/freeze/fuel", false);
 }
 
@@ -562,10 +562,10 @@ parse_option (const string& arg)
         fgSetBool("/sim/freeze/fuel", false);
     } else if ( arg == "--enable-fuel-freeze" ) {
         fgSetBool("/sim/freeze/fuel", true);
-    } else if ( arg == "--disable-tod-freeze" ) {
+    } else if ( arg == "--disable-clock-freeze" ) {
-        fgSetBool("/sim/freeze/time-of-day", false);
+        fgSetBool("/sim/freeze/clock", false);
-    } else if ( arg == "--enable-tod-freeze" ) {
+    } else if ( arg == "--enable-clock-freeze" ) {
-        fgSetBool("/sim/freeze/time-of-day", true);
+        fgSetBool("/sim/freeze/clock", true);
     } else if ( arg == "--disable-anti-alias-hud" ) {
 	fgSetBool("/sim/hud/antialiased", false);
     } else if ( arg == "--enable-anti-alias-hud" ) {
@@ -1117,8 +1117,8 @@ fgUsage ()
          << "    --enable-freeze               Start in a frozen state" << endl
          << "    --disable-fuel-freeze         Fuel is consumed normally" << endl
          << "    --enable-fuel-freeze          Fuel tank quantity forced to remain constant" << endl
-         << "    --disable-tod-freeze          Time of day advances normally" << endl
+         << "    --disable-clock-freeze        Clock advances normally" << endl
-         << "    --enable-tod-freeze           Do not advance time of day" << endl
+         << "    --enable-clock-freeze         Do not advance clock" << endl
          << "    --control=mode                Primary control mode (joystick, keyboard," << endl
          << "                                  mouse)" << endl
          << "    --enable-auto-coordination    Enable auto coordination" << endl