Fix map issues with librequake multiplayer

[pnahratow]

• Librequake e1m1 is different from Quake e1m1. This is a problem when joining multiplayer games.
• The sourceports that autodownload missing maps will not do so for the stock maps dm1, dm2, etc. So you cannot join games with quake players.
• The map menu when starting a multiplayer server show only original quake maps and not the librequake ones. This is hardcoded in menu.c

It would be awesome to be able to just play multiplayer with librequake. Lets fix these issues.
First we need ideas though.

[MotoLegacy]

@lavenderdotpet can we enable Discussions for this repository and move this to a discussion? We shouldn't treat this as an Action Item yet, so moving it away from Issues would be great :)

[lavenderdotpet]

@lavenderdotpet can we enable Discussions for this repository and move this to a discussion? We shouldn't treat this as an Action Item yet, so moving it away from Issues would be great :)

we have discussions https://github.com/lavenderdotpet/LibreQuake/discussions

[MotoLegacy]

Can you convert it to a discussion then, as per the second part of the question? Thanks