When disabling/enabling elrail, there is an assumption that `engclass` of 2
means the engine will run on elrail. While this holds for default engines,
NewGRFs can do other things.
To resolve this we store the intended railtype so that toggling elrail will
restore to the correct type.
This is using a non-intrusive type-traits like templated system, which
allows compile-time validation that the command table and the command
enum match up.
Soon we will make "join game" join the game as spectator first,
so limiting the amount of spectators makes no sense anymore in
that context. Not sure it ever did make sense.
TURN is a last resort, used only if all other methods failed.
TURN is a relay approach to connect client and server together, where
openttd.org (by default) is the middleman.
It is very unlikely either the client or server cannot connect to
the STUN server, as they are both already connected to the Game
Coordinator. But in the odd case it does fail, estabilishing the
connection fails without any further possibility to recover.
In this mode you do register to the Game Coordinator, but your
server will not show up in the public server listing. You can give
your friends the invite code of the server with which they can
join.
This removes the need to know a server IP to join it. Invite codes
are small (~7 characters) indentifiers for servers, which can be
exchanged with other players to join the servers.
This reduced the load on compilers, as currently for example MacOS
doesn't like the huge settings-tables.
Additionally, nobody can find settings, as the list is massive and
unordered. By splitting it, it becomes a little bit more sensible.
We no longer need them. If you want to remove a field .. just
remove it! Because of the headers in the savegame, on loading,
it will do the right thing and skip the field.
Do remember to bump the savegame version, as otherwise older
clients can still load the game, but will reset the field you
have removed .. that might be unintentially.
We won't be able to make it fully self-descriptive (looking at you
MAP-chunks), but anything else can. With this framework, we can
add headers for each chunk explaining how each chunk looks like
in detail.
They also will all be tables, making it a lot easier to read in
external tooling, and opening the way to consider a database
(like SQLite) to use as savegame format.
Lastly, with the headers in the savegame, you can freely add
fields without needing a savegame version bump; older versions
of OpenTTD will simply ignore the new field. This also means
we can remove all the SLE_CONDNULL, as they are irrelevant.
The next few commits will start using this framework.
We often ask people for their openttd.cfg, which now includes their
passwords, usernames, etc. It is easy for people to overlook this,
unwillingly sharing information they shouldn't.
By splitting this information over either private.cfg or secrets.cfg,
we make it more obvious they shouldn't be sharing those files, and
hint to what is inside them.
With std::variant all memory can be figured out at compile time, so the compiler needs to keep track of fewer elements. It also saves out a unique_ptr and its memory management, over a slight impact for resolving a setting.
