PKG update [attempt #2]

[Juan Pablo Carbajal]

Hi all

To test the updated version, I wrote all commands that need to be
working. Did I forget something?
http://wiki.octave.org/User:KaKiLa#updating_pkg.m

Please also add the new desired functionality (like pkg install
-make_opt "-j7" pkg_name )

The only difference in interface is that the option
{local,global}_list is now called {local,global}_db. However these
aspect of pkg.m is under review by jwe at the moment.

If inputParser is ported to core, then the function will become
cleaner and easier to read/maintain.

Cheers