Fix renderlights loaded from savegames aliasing other lights

Some entities wrote the handle from gameRenderWorld->AddLightDef()
into savegames and reused it after restoring it.
That's a bad idea, because at that point the handle most likely belongs
to something else (likely some idLight). The most visible issue this
can create is that the flashlight may not work correctly after loading
a savegame with flashlight on, when it happens to alias a light that's
updated each frame to (mostly) being off..

The correct way to handle this (THAT FOR SOME REASON WAS ALREADY
IMPLEMENTED IN D3XP BUT NOT THE BASE GAME - WHY?!) is to get a fresh
handle with AddLightDef() when restoring a savegame - unless the handle
was -1, which means that the light didn't exist when saving.

fixes #495

game/Moveable.cpp

@@ -810,6 +810,15 @@ void idExplodingBarrel::Restore( idRestoreGame *savefile ) {
 	savefile->ReadInt( particleTime );
 	savefile->ReadInt( lightTime );
 	savefile->ReadFloat( time );
+
+	// DG: enforce getting fresh handle, else this may be tied to an unrelated light!
+	if ( lightDefHandle != -1 ) {
+		lightDefHandle = gameRenderWorld->AddLightDef( &light );
+	}
+	// DG: same for render entity
+	if ( particleModelDefHandle != -1 ) {
+		particleModelDefHandle = gameRenderWorld->AddEntityDef( &particleRenderEntity );
+	}
 }
 
 /*

game/Projectile.cpp

@@ -157,6 +157,11 @@ void idProjectile::Restore( idRestoreGame *savefile ) {
 
 	savefile->ReadRenderLight( renderLight );
 	savefile->ReadInt( (int &)lightDefHandle );
+	// DG: enforce getting fresh handle, else this may be tied to an unrelated light!
+	if ( lightDefHandle != -1 ) {
+		lightDefHandle = gameRenderWorld->AddLightDef( &renderLight );
+	}
+
 	savefile->ReadVec3( lightOffset );
 	savefile->ReadInt( lightStartTime );
 	savefile->ReadInt( lightEndTime );

game/Weapon.cpp

@@ -453,12 +453,21 @@ void idWeapon::Restore( idRestoreGame *savefile ) {
 
 	savefile->ReadInt( guiLightHandle );
 	savefile->ReadRenderLight( guiLight );
-
+	// DG: we need to get a fresh handle, otherwise this will be tied to a completely unrelated light!
+	if ( guiLightHandle != -1 ) {
+		guiLightHandle = gameRenderWorld->AddLightDef( &guiLight );
+	}
 	savefile->ReadInt( muzzleFlashHandle );
 	savefile->ReadRenderLight( muzzleFlash );
+	if ( muzzleFlashHandle != -1 ) { // DG: enforce getting fresh handle
+		muzzleFlashHandle = gameRenderWorld->AddLightDef( &muzzleFlash );
+	}
 
 	savefile->ReadInt( worldMuzzleFlashHandle );
 	savefile->ReadRenderLight( worldMuzzleFlash );
+	if ( worldMuzzleFlashHandle != -1 ) { // DG: enforce getting fresh handle
+		worldMuzzleFlashHandle = gameRenderWorld->AddLightDef( &worldMuzzleFlash );
+	}
 
 	savefile->ReadVec3( flashColor );
 	savefile->ReadInt( muzzleFlashEnd );
@@ -516,6 +525,9 @@ void idWeapon::Restore( idRestoreGame *savefile ) {
 
 	savefile->ReadInt( nozzleGlowHandle );
 	savefile->ReadRenderLight( nozzleGlow );
+	if ( nozzleGlowHandle != -1 ) { // DG: enforce getting fresh handle
+		nozzleGlowHandle = gameRenderWorld->AddLightDef( &nozzleGlow );
+	}
 
 	savefile->ReadVec3( nozzleGlowColor );
 	savefile->ReadMaterial( nozzleGlowShader );