FRZZ and FRZW changes/fixes

Fix FRZW low temperature transition (accidentally turned into a high temperature transition in b661418d).
FRZZ now melts into FRZW, so that single pixels "form ice that always cools" as in FRZZ description.
ICE update function: was meant to be checking not setting parts[i].ctype. However, turning FRZZ into self-cooling ice seems a logical thing to do, so set ctype of parts[r>>8].ctype, and make all types of ice cause this reaction (not just ICE(FRZW) as was apparently the original intention of the ctype check).

src/simulation/elements/FRZW.cpp

@@ -37,10 +37,10 @@ Element_FRZW::Element_FRZW()
 	LowPressureTransition = NT;
 	HighPressure = IPH;
 	HighPressureTransition = NT;
-	LowTemperature = ITL;
+	LowTemperature = 53.0f;
-	LowTemperatureTransition = NT;
+	LowTemperatureTransition = PT_ICEI;
-	HighTemperature = 53.0f;
+	HighTemperature = ITH;
-	HighTemperatureTransition = PT_ICEI;
+	HighTemperatureTransition = NT;
 	
 	Update = &Element_FRZW::update;
 	

src/simulation/elements/FRZZ.cpp

@@ -40,7 +40,7 @@ Element_FRZZ::Element_FRZZ()
 	LowTemperature = 50.0f;
 	LowTemperatureTransition = PT_ICEI;
 	HighTemperature = 273.15;
-	HighTemperatureTransition = PT_WATR;
+	HighTemperatureTransition = PT_FRZW;
 	
 	Update = &Element_FRZZ::update;
 	

src/simulation/elements/ICEI.cpp

@@ -70,8 +70,11 @@ int Element_ICEI::update(UPDATE_FUNC_ARGS)
 						return 0;
 					}
 				}
-				else if (((r&0xFF)==PT_FRZZ) && (parts[i].ctype=PT_FRZW) && !(rand()%200))
+				else if (((r&0xFF)==PT_FRZZ) && !(rand()%200))
+				{
 					sim->part_change_type(r>>8,x+rx,y+ry,PT_ICEI);
+					parts[r>>8].ctype = PT_FRZW;
+				}
 			}
 	return 0;
 }