Feature: [Network] Ensure players fill in a name instead of defaulting to "Player"

src/network/network_func.h

@@ -37,6 +37,8 @@ extern StringList _network_ban_list;
 
 byte NetworkSpectatorCount();
 bool NetworkIsValidClientName(const char *client_name);
+bool NetworkValidateClientName();
+bool NetworkValidateClientName(char *client_name);
 void NetworkUpdateClientName();
 bool NetworkCompanyHasClients(CompanyID company);
 const char *NetworkChangeCompanyPassword(CompanyID company_id, const char *password);