- Fix the last few bugs I could find with thing args
- Move version update code
- Rename internal variables to `thing_[string]args` to make older code merge issues more obvious
Map things are writeable in Lua, which I am pretty certain is a mistake because mapthings are not sent over the network at all. I considered making them net-synced (it would be relatively easy), but it also aligns with another, more "philosophical" issue: Doom generally copies over properties from mapthing_t into mobj_t, and then only refers to it again when needing to respawn an object -- mapthing_t is not really intended to be referred to very often at runtime. At best it's slightly annoying since some objects rely on a spawnpoint for behavior changes, at worst it may make ACS more confusing in the future since Thing and Mobj tags are mixed together or less useful since they wouldn't be able to modify behaviors of objects that are based on args.
So I decided to solve these two issues at the same time; just treat mapthing_t as something to copy values from, like OG Doom does it. This basically just means that special and args are also part of the mobj now instead of the mapthing, which should fill any desire to edit this stuff from Lua, and reduces the number of instances where objects need to check for their spawnpoint to function properly.
