Port netcode fixes from SRB2 Classic

This ports almost all netcode-related changes from SRB2 Classic. Too lazy to write a full description though xdxdxd

Note that some of them were skipped, either because we don't want them, because I plan to port them separately or because they were already in. Here is the (hopefully accurate) list of commits that are NOT included:

• ddf8a189 Increase size of mapname in serverinfo_pak
• 010b04c527a8e9038bbaca77b3af78b9d6e4777a Merge remote-tracking branch 'stjr/next' into reveries
• a5312e40 Update i_tcp.c
• c41a4605 Check for ENODEV for hosts with IPv6 disabled while running in IPv6 mode
• 443d6b52 Fix connections not timing out if clients haven't joined yet
• c9eaa6bd Edit i_tcp.c
• ba8fd3de36612d8f0fb7350e5d04246f8f20aa4d Fix game input still registering in menus
• 8ed8d32250ddadffa528ca5d8f593d4dfde01273 Merge Read and Write of Mobj in savedata
• 00468a4e66a5b49f8aba0ff2a916aa97e8c8a2e8 Merge read and write for Lua gamedata
• dc3dc1be7d2089a9fe6fc6ae4a6aaefa9315059f Port of an enchanced version of server info view from luigi budd's fork Remove unnecesary things like arrow animation and connection music
• 2dcabf17598a16f48369da89ad86866c017ed713 Remove an hashtag
• aa6cf4cc8af6d68c4bdccafafec1b808068d93b1 Fix Windows build
• 5c855f9b56d4debe3d2342222894bac940e3e75e Change some details about the screen
• 5a522671c3265f4e5a5d15544226cbadcc9925a1 Make constant uppercase and fix some magic numbers
• 4f71e50d95086c64bf23cc486c9471baec98aeee Add setting for toggling local packet loss
• 8931b1fd3c6930e30dcc9c85690c87678d90016c Make PlayerQuit hook to not be called by bots
• cfd8bb4fcfc2572e21391ada1184e42433465b2e Fix bots causing player slots to disappear