compatibilty for steam interface v9

[mithrand0]

Note: I have a modified engine.dll locally, that needs this. Without a patched engine, it won't work.

This PR is a draft, a proof of concept. It works, but is not production quality, in any way.

Probably, a lot still needs to be tested, but this is the status. Finding below are with the latest Steam SDK:

What works:

Client

• Client starts
• Confirmed with latest steam_api.dll
• Main screen seems to work
• Workshop items from Steam do load
• Client can find and join lobbies.

What doesnt:

• player reporting
• steam inventory

Both caused by parameters, that don't exist anymore, are renamed. These issues are in game code, should be doable to locate and replace.

Server

• Server starts
• Confirmed with latest steam_api.dll
• Gameserver is inited from game code instead of engine and listens on correct ip+port
• Heartbeat to master servers is sent out
• Server can be joined.
• Workshop items can be downloaded with rd_enable_workshop_item

What doesn't:

• server crashes on steam investory calls, i.e. when a mission ends. This is an issue in the game code, and should be doable to locate and replace.

I think it's promising, and surprisingly, joining lobbies works from both ends. Probably, once this is tested further, other issues arise, but all these should be in the game code itself.