bug - knights won't automatically spawn if any Knight0 already in Inventory

[tlongstretch]

inside Inventory.cc's Inventory::specialize_serf
...
if (serfs[type] != 0) {
return false;
}
...

fix (applied in my fork)
// must exclude Knights from this check!
if (serfs[type] != 0 && !(type >= Serf::TypeKnight0 && type <= Serf::TypeKnight4)) {
return false;
}

[tlongstretch]

I assume this was intended to prevent creation of new specialist (non-knight) when an existing one could be sent out, but should not be applied to knights