customizable Lua "panic" behavior

["Eric Ries" <eries@...>]

When Lua gets into a reall bad error (one for which no error handler is
available) it calls exit. For situations where Lua is being used in an
embedded context, this is terrible, because it means the host application
quits without so much as a core file, making these kinds of errors hard to
track down.

In our app, we have hacked this (which is easy) to call our custom error
handler which produces much nicer behavior. It would be nice if each app
didn't have to hack this but rather if there was a standard Lua way to have
this happen.

The patch would be quite simple, and it could be on either a per-lua_State
basis or simply a global behavior. I would be happy to write it if there is
interest.

Eric