Network: implement 0.4 marked compatibility removals

[Berserker66]

trafficstars

These changes should all have been documented at least a month ago. People testing their clients would be appreciated. The python clients should all be fine, even 0.3.3 clients worked in my testing, though they will say "No player connected". - But again, additional testing won't hurt.

[Berserker66]

Unless I get a lot of green lights quite soon, my intention is to merge this after our next release.

[black-sliver]

apclientpp :heavy_check_mark:

• games are a set since version 0.2.6; never used the index
• GetDataPackage["games"] since 0.2.6
• items_handling since 0.2.0
• never supported datapackage_version (the single int)

[black-sliver]

apcpp :heavy_check_mark:

• does not seem to use RoomInfo["games"]
• items_handling is being sent since 0.2.2
• datapackage_version would become always 0, but caching is currently not implemented afaik
• uses neither exclusions nor games in GetDataPackage