Fixed punctuation consistency

apps/openmw/mwworld/class.cpp

@@ -134,12 +134,12 @@ namespace MWWorld
 
     void Class::setRemainingUsageTime (const Ptr& ptr, float duration) const
     {
-        throw std::runtime_error ("class does not support time-based uses.");
+        throw std::runtime_error ("class does not support time-based uses");
     }
 
     float Class::getRemainingUsageTime (const Ptr& ptr) const
     {
-        throw std::runtime_error ("class does not support time-based uses.");
+        throw std::runtime_error ("class does not support time-based uses");
     }
 
     std::string Class::getScript (const Ptr& ptr) const