Allow module-level literal lists (Fixes #113).

This fixes http://trac.cython.org/cython_trac/ticket/113.

On a related note, "Literal list must be assigned to pointer at time of declaration" limitation seems arbitrary, maybe it's worth removing it?
It was introduced in d3c79c9b1d3c89c9ec31c517e051264ad8fac287 and I'm not seing why it is necessary at all.