Netcode hotfix

Various netcode fixes are included in this branch. Most important of all of course is a fix for the Net_CloseConnection invalid node -32769 detected message thing, or rather what actually caused that to occur.

It's a merge to master since everything here should be compatible with 2.1.18: the only main changes are related to recieving packets (whether you're the host of a netgame or a client), which AFAIK shouldn't cause desyncs if you played with these fixes on a 2.1.18-hosted netgame (or hosted a netgame with the fixes and 2.1.18-using players join you).

See merge request !185

Cleanup part 2, make ye old 2.1.18 warning a debugfile only message, and make the node == -1 have its own debugfile only message too

Also get rid of a stray newline

textcmd[0] for PT_NODETIMEOUT can't hold anything < 0 anyway, and you'd probably have to really try to get >= MAXNETNODES

Display node's IP when printing the "sending file to node n" message, if noticedownload is turned on

* if you sent it to a client rather than the server, game over, your connection is closed
* if files that don't exist or are too large are requested are listed, game over, your connection is closed (they should have been checked on YOUR side beforehand, silly)
* if the server has downloading disabled anyway, ...yeah, you get the idea

Don't worry, I made sure Got_RequestFilePak cleaned up the full file request list for the node in case of failure

Exit your server desync fix

This branch fixes this bug: https://mb.srb2.org/showthread.php?t=41811

Here's an explanation of how this bug is actually happening:
* Pressing Enter with "Start" selected calls `D_MapChange` to make a map change command. (Note that part of it is actually delayed because it's called from a menu, but this isn't relevant to the bug)
* `D_MapChange` itself calls `SV_StartServer` to start up the server, if you're supposed to be the server player.
* Pressing Esc while starting up a server like shown in the gif causes the server to be cancelled, and go back to the title screen.
* HOWEVER, since we're still in `D_MapChange`, the map change command is made anyway.
* Since we're not in a netgame as expected, no random seed is added, and the map change command has a total size of 9 bytes (1 for the id + 8 for the actual data). This is then stored in the net command buffer. The random seed would add another 4 bytes if it WAS added, note.
* Next time you start a server, and let it work as normal, two more net commands are added: an "add player" command (size 3), and a map change command (size 13, including random seed this time). Your net command buffer now has a total size of **25** (9 + 3 + 13).
* This net command buffer is then sent as a `PT_TEXTCMD` packet to yourself.
* SRB2 recieves the `PT_TEXTCMD` you sent to yourself, and some time later, tries to run the net commands stored in it.
* The first map command is read as if it's size 13 rather than size 9 (it isn't), mistakeningly thinking a 4-byte random seed is stored (since you ARE in a netgame now). This means your buffer reads what it thinks is the next net command starting from position **[14]** in the buffer.
* Bad luck, it gets an id of **0**, which doesn't correspond with any net command!
* This message is then printed in the console:

> WARNING: Got unknown net command [14]=0 (max 25)

* The game subsequently kicks you out the server with a "desynch" message.

tl;dr The game doesn't correctly cancel the map change when you cancel the server with Esc like that. This is not a good thing.

See merge request !188

Added a bunch of missing checks to prevent non-server players from sending other non-server players stuff

Dedicated bonuses fix

Fixes the issue reported here: https://mb.srb2.org/showthread.php?t=42530

What it turns out is going on is that making the game bail out in the middle of Y_StartIntermission if you're a dedicated server's host prevents the game from awarding the players bonuses in coop mode. Therefore it's not just special stage bonuses, but ANY kind of bonuses that can cause desyncs if someone loses all their lives.

This can be merged to master since it's a change only for dedicated server hosts, and should otherwise be compatible with 2.1.18.

See merge request !186

On second thought, this was probably unnecessary anyway.

This reverts commit 1078a642.

Don't bail out in Y_StartIntermission in dedicated mode, this causes the game not to add on score bonuses for players from the server's view of things!

SDL fixes and cleanup

Mostly cleanup tbh. I noticed a few things that bugged me when examining SDL's code recently, thought I might as well fix them up a bit.

These changes definitely does not affect netplay, so this can be merged to master just fine.

See merge request !183

I_GetConsoleEvents: Split KEY_EVENT code into a function of its own, like with I_GetEvent's event types

One benefit of this is that event_t data need only be created if KEY_EVENT is found, since the other event types never do anything anyway

Not really important or anything, but checking render_soft == rendermode rather than rendermode == render_soft always bugged me. And it's not consistent with the rest of the source code (or at least most of it) anyway.

If modenum was < 0 or >= MAXWINMODES, that would make windowedModes[modeNum] be out of bounds and possibly crash the game.

I_FinishUpdate: OglSdlFinishUpdate should never run for render_soft, even if screens[0] somehow is NULL

Update to v2.1.18

Exactly what it says on the tin.

See merge request !180

Don't worry, I remembered to update MODVERSION as well this time :)

Jet Jaw crash fix

Turns out not having MF_SHOOTABLE can cause the Jet Jaw to endlessly loop between the two states, until somehow LUA_CallAction inexplicably causes Z_StrDup to crash anyway (that one's a mystery to me, I'm not going to look into it right now). I tweaked A_JetJawChomp so this endless loop can't happen anymore.

See merge request !176

Invalid node hotfix master

Quick hotfix to prevent `Net_CloseConnection` from crashing if the node's number is invalid.

See merge request !179