Fix return type of ParticleSystem:getAreaSpreadIsRelativeDirection, remove optional parameters from ParticleSystem:setAreaSpread (resolves #1340)

I opted to remove the optional parameters altogether since they seemed oddly
out-of-place. They used to reset the values to defaults when not supplied, and
they also weren't returned by getAreaSpread(), so
setAreaSpread(getAreaSpread()) actually changed spread parameters.

The other option was to remove the separate getters/setters for
AreaSpreadIsRelativeDirection and AreaSpreadAngle, and fully rely on
setAreaSpread for these parameters, but the rest of the ParticleSystem API
tends to keep parameters separate.

--HG--
branch : minor

src/modules/graphics/wrap_ParticleSystem.cpp

@@ -201,8 +201,7 @@ int w_ParticleSystem_setAreaSpread(lua_State *L)
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
 
 	ParticleSystem::AreaSpreadDistribution distribution = ParticleSystem::DISTRIBUTION_NONE;
-	float x = 0.f, y = 0.f, angle = 0.f;
-	bool isRelativeDirection = false;
+	float x = 0.f, y = 0.f;
 
 	const char *str = lua_isnoneornil(L, 2) ? 0 : luaL_checkstring(L, 2);
 	if (str && !ParticleSystem::getConstant(str, distribution))
@@ -214,11 +213,9 @@ int w_ParticleSystem_setAreaSpread(lua_State *L)
 		y = (float) luaL_checknumber(L, 4);
 		if (x < 0.0f || y < 0.0f)
 			return luaL_error(L, "Invalid area spread parameters (must be >= 0)");
-		angle = (float) luaL_optnumber(L, 5, 0.0);
-		isRelativeDirection = luax_optboolean(L, 6, false);
 	}
 
-	t->setAreaSpread(distribution, x, y, angle, isRelativeDirection);
+	t->setAreaSpread(distribution, x, y);
 	return 0;
 }
 
@@ -263,7 +260,7 @@ int w_ParticleSystem_setAreaSpreadIsRelativeDirection(lua_State *L)
 int w_ParticleSystem_getAreaSpreadIsRelativeDirection(lua_State *L)
 {
 	ParticleSystem *t = luax_checkparticlesystem(L, 1);
-	lua_pushnumber(L, t->getAreaSpreadIsRelativeDirection());
+	luax_pushboolean(L, t->getAreaSpreadIsRelativeDirection());
 	return 1;
 }