Pull request/move to lua52 module style

I've converted all the modules that don't fiddle with lua core modules
(mainly the _ext and _init suffixed modules) to the `lua 5.2' module
style.  Tested lightly by hand, and checked that the Zile test suite
still finishes without error when using my  ```next``` branch (which
is just a merge of all pending pull requests against master for integration
testing).