encapsulate protected Lua calls with a coroutine based loop
Coxpcall encapsulates the protected calls with a coroutine based loop,
so errors can be handled without the usual pcall/xpcall issues with
coroutines.

Using Coxpcall usually consists in simply loading the module and then
replacing Lua pcall and xpcall by copcall and coxpcall.

Maintainer: The OpenBSD ports mailing-list <ports@openbsd.org>

WWW: http://coxpcall.luaforge.net/
