Article requests

In a way this ticket is the follow-up to #610, it's meant to be a collection of specific articles that would be good to write. I expect to slowly trickle some of these when I have some time and am unable to do anything technical, but if somebody makes a specific request I could prioritize it.

* lua states (luaui, luarules x2, luagaia, various luaparsers) ~~+ inter- and intra- state communication~~
* unsynced vs synced
* units vs features
* COB vs LUS? also scripting in general
* ~~rules params vs modoptions vs modrules?~~
* basecontent primer?
* wupget handlers?
* commands (stateful vs regular, cmd.insert/remove, cmd tags, unsynced commands)
* s3o vs dae (vs others, vs 3do?)
* chakras
* CEG basics?
* ~~yardmaps, footprints, speed mod classes?~~
* ~~what does starting a game look like? autohost, lobbyserver, lobbyclient, engine - who does what? what is a startscript?~~
* ~~replay format, network traffic (message queue vs ping), why no rejoin~~
* what actually gets loaded (i.e. `defs.lua` and `luaui.lua` and not individual defs or wupgets)? maybe belongs to some level of ABC template/tutorial though? i guess freeform writing is easier to produce than a valid mod though
* canonical lua ways to add classic rts features (support powers, research, supply, unit abilities, ...)?

Feel free to add more.