* Make Sides = {"gbr", "ger" ..} from sidedata.lua available to all defs
* Make a Obstacles base class for mines & tank obstacles
* Autogenerate per-side mines in a normal unitdef file instead of in unitdefs_post
* Make a Null base class for sorties, squads, etc
* Autogenerate sortie and squad defs in a normal unitdef file instead of in unitdefs_post (via gamedata/unitdef_autogen.lua)