Rename wrapper.pyx to libzim.pyx.

This is "the" name of the python module created. Let's call it correctly.
Let's use "wrapper" for the internal library wrapping the C++ code.

Author: mgautierfr

libzim/libwrapper.cpp

@@ -23,7 +23,7 @@
 #include <Python.h>
 #include "libwrapper.h"
 
-#include "wrapper_api.h"
+#include "libzim_api.h"
 
 #include <cstdlib>
 #include <iostream>

libzim/wrapper.pyx renamed to libzim/libzim.pyx

@@ -88,7 +88,7 @@ def get_long_description():
 
 wrapper_extension = Extension(
     name="libzim",
-    sources=["libzim/wrapper.pyx", "libzim/libwrapper.cpp"],
+    sources=["libzim/libzim.pyx", "libzim/libwrapper.cpp"],
     include_dirs=["libzim", LIBZIM_INCLUDE_DIR],
     libraries=["zim"],
     library_dirs=[LIBZIM_LIBRARY_DIR],