Sweatshop workers never become unproductive due to drops in local demand; they're assumed to be working for export.
This means sweatshops can be used as a way to protect the productivity of your menial workers.
Make menial productivity calculations more consistent; fixes a discontinuity where adding one single menial worker could drop your menial productivity by 40% or more.

Simplify "chooses own job" system.  Remove two-pass system (and the "2" state for `slave.choosesOwnAssignment`) and global variable, consolidate job-printing logic, fix a few bugs, and improve error handling.

Removes `$oldACitizens` global state variable.
Make sure `NCSYouthening` is defined on the player object.
A few typo corrections.
Migrates `reCitizenHookup` to use the same (more robust) FS key mechanism as `reMaleCitizenHookup`.
Fix some bad ledger entries.
Clean up migration of player fertility drugs from `fertDrugs`.
Some fixes for `RESS Gorging`.

Clamp skin stretch scaling at 45 years old.  I'm not convinced about the utility of elasticity in this application, but at least we can prevent total calcification of elderly slaves, which is clearly wrong.