Add game saves about quipkit HOT 2 CLOSED

Saving Lua tables to files is complicated by the fact that their metatable relationships need to be restored on load somehow. I can't use persistence libraries that save metatables with regular ones, since that could lead to subtle bugs involving old and new metatable code when loading games.

I need to test existing persistence libraries to find if they're suitable, or can be adapted to this end.

from quipkit.

Let tables be saved/loaded with metatables kept.

• Closed by 2ba932c.
• Try ./game test/persistsave.lua, then ./game test/persistload.lua.
  Observe the messages and numbers displayed at the command line.
• With persist.lua, tables, strings, numbers and the names of
  metatables are saved. When loading a table, the metatables of
  the saved tables are restored to metatables with the same name.
  This only works if the metatables are public, i.e. not local.
• When saving, env can hold things like loaded Lua packages.
  When loading, a hook function can be passed and is called before
  loading the table data, so e.g. required Lua packages can be
  reloaded.

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