- system alias no longer persists after system delete

- reset some character table columns on corp change or character sold

app/main/model/systemmodel.php

@@ -394,6 +394,8 @@ class SystemModel extends BasicModel {
 
         if( !$self->isActive()){
             // system becomes inactive
+            $self->alias = '';
+
             // reset "rally point" fields
             $self->rallyUpdated = 0;
             $self->rallyPoke = false;