[proposal] Libary changes

[Sebastien Lai <237482@...>]

Before I start: This proposal might or might not be somewhat biased on
my previous experience with modular programming languages like python
and co.

What I bothered me most about Lua is the way global
"more-or-less-constant" variables are declared - meaning especially
_G, _VERSION, and the variable "arg" containing the arguments vector
passed to 'main' in the native environment (usually C and/or C++, but
also Java, CSharp, etc).

What I propose is to create a new module named "sys", that will
respectively contain that data instead, like:

   sys.argv instead of arg
   sys.globals instead of _G
   sys.version instead of _VERSION

In my opinion, that would make more readable, and possibly avoid
ambigious re-declaration of 'arg' (that unfortunately happened to me
before, when I learned Lua, for example).

Having a 'sys' module might also make it more interesting to share
some more lowlevel information acquirable through the C
standardlibrary with Lua, instead of polluting the global namespace.

And, similar to 'os' and 'io', this module should be part of the
global namespace.

What do you guys think?