Fix: Treat closing network relay window as a choice of "No".

Issue ConnectFailure when closing the window if the relay request is
considered unhandled.

Codechange: automatic adding of _t to (u)int types, and WChar to char32_t

for i in `find src -type f|grep -v 3rdparty/fmt|grep -v 3rdparty/catch2|grep -v 3rdparty/opengl|grep -v stdafx.h`; do sed 's/uint16& /uint16 \&/g;s/int8\([ >*),;[]\)/int8_t\1/g;s/int16\([ >*),;[]\)/int16_t\1/g;s/int32\([ >*),;[]\)/int32_t\1/g;s/int64\([ >*),;[]\)/int64_t\1/g;s/ uint32(/ uint32_t(/g;s/_uint8_t/_uint8/;s/Uint8_t/Uint8/;s/ft_int64_t/ft_int64/g;s/uint64$/uint64_t/;s/WChar/char32_t/g;s/char32_t char32_t/char32_t WChar/' -i $i; done

Codechange: ensure OnConnect() always gets called with a valid socket (#9729)

This should already be the case, but now assert()s will tell us
if this isn't.

Fix: [Network] show query errors in the server listing instead of error popup (#9506)

When you are query several servers at once, it is rather unclear
for which server you got a popup. Instead, show any errors on the
server itself.

This is only true for the query-part. Joining a server still gives
an error popup to tell you about any issue.

Fix #9492: show for what server a relay session is being created (#9494)

Currently it says "the server" which is a bit ambigious. Be more
specific.

Fix: report reuse of invite-code and switch to local game-type (#9487)

This prevents two servers battling for the same invite-code. Now
the last one wins.

Feature: allow the use of TURN to connect client and server together

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.

Feature: [Network] Optionally send NewGRF names with NewGRFs in GameInfo

Before 8a2da49 the NewGRF names were synchronized using UDP packets, however
those have been removed. With this a new version of the GameInfo packet is
introduced that allows to specify the type of serialisation happens for
NewGRFs. Either only the GRF ID and checksum, or those two plus the name of
the NewGRF.
On this request for local servers will send the NewGRFs names.
The Game Coordinator will get the names on the first registration, and after
that only the GRF ID and checksum.

Feature: allow the use of STUN to connect client and server together

This method doesn't require port-forwarding to be used, and works for
most common NAT routers in home setups. But, for sure it doesn't work
for all setups, and not everyone will be able to use this.

Add: allow setting your server visibility to "invite-only" (#9434)

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.

Feature: join servers based on their invite code

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.

Feature: allow setting (game) coordinator and content server connection strings using environment variables

OTTD_COORDINATOR_CS for the game coordinator defaults to coordinator.openttd.org:3976
OTTD_CONTENT_SERVER_CS for the content server defaults to content.openttd.org:3978
OTTD_CONTENT_MIRROR_CS for the content mirror server defaults to binaries.openttd.org:80