Fix rendering of Unit::ThermalConductivity

The old behaviour was:
>>> Quantity('0.9 W/m/K').UserString
u'0.00 W/mm/K'
>>> Quantity('1.1 W/m/K').UserString
u'1.10 W/m/K'
>>> Quantity('1100 W/m/K').UserString
u'1100.00 W/m/K'

The new behaviour is:
>>> Quantity('0.9 W/m/K').UserString
u'0.90 W/m/K'
>>> Quantity('1.1 W/m/K').UserString
u'1.10 W/m/K'
>>> Quantity('1100 W/m/K').UserString
u'1.10 W/mm/K'

src/Base/UnitsSchemaInternal.cpp

@@ -114,7 +114,7 @@ QString UnitsSchemaInternal::schemaTranslate(const Quantity &quant, double &fact
         }
     }
     else if (unit == Unit::ThermalConductivity) {
-        if (UnitValue < 1000) {
+        if (UnitValue > 1000000) {
             unitString = QString::fromLatin1("W/mm/K");
             factor = 1000000.0;
         }

src/Base/UnitsSchemaMKS.cpp

@@ -143,7 +143,7 @@ QString UnitsSchemaMKS::schemaTranslate(const Quantity &quant, double &factor, Q
         }
     }
     else if (unit == Unit::ThermalConductivity) {
-        if (UnitValue < 1000) {
+        if (UnitValue > 1000000) {
             unitString = QString::fromLatin1("W/mm/K");
             factor = 1000000.0;
         }