Ignoring the removed job types for DF 0.40+

The version check allows the plugin to work with DF 0.34, just in case.
Localizing a few Lua variables.

It seems like the globals could be localized, too, but I'm not quite sure what that would accomplish.
Moving the global job_types cache into the two functions that use it.

It's mostly an artifact of a misunderstanding, anyway.
Warning about mismatched stockflow entries.

For the most part, mismatches should only happen if the reaction list has changed between world loads, which means either the raw files or the plugin files have been changed.  For now, such entries are ignored, though in some cases it might be possible to recover a new order number by searching through the reaction list.
Deleting old stockflow records.

Once a stockpile has been removed or abandoned, its persistent configuration is obsolete.
Faster stockflow mode, ignoring the bookkeeper.
Documenting the new Stockflow option.
Slightly better stockflow description.
Merge pull request #275 from eswald/stockflow-40

Stockflow Improvements