llhttp: s/llhttp/lib/, add llhttp/__init__

Move the external sources from llhttp/ to lib/, compile the external module
as __llhttp instead of llhttp, and add an llhttp/__init__ that imports the
compiled module into the existing namespace.  This makes it easier to add
additional python code to the module without changing the module's name.

MANIFEST.in

@@ -1 +1 @@
-include llhttp/llhttp.h
+include lib/llhttp.h

llhttp/__init__.py

@@ -0,0 +1,2 @@
+from __llhttp import *
+__all__ = ("Request", "Response")

pyllhttp.c

@@ -3,7 +3,7 @@
 #include <stdbool.h>
 #include <string.h>
 #include <ctype.h>
-#include "llhttp/llhttp.h"
+#include "lib/llhttp.h"
 
 #define STRING(x) #x
 #define XSTRING(x) STRING(x)
@@ -435,7 +435,7 @@ snake_to_camel(char * string) {
 }
 
 PyMODINIT_FUNC
-PyInit_llhttp(void) {
+PyInit___llhttp(void) {
     PyObject *m = PyModule_Create(&llhttp_module);
     if (!m)
         return NULL;

setup.py

@@ -25,13 +25,14 @@
         "Topic :: Internet :: WWW/HTTP :: HTTP Servers",
         "License :: OSI Approved :: MIT License",
     ],
-    headers = [ "llhttp/llhttp.h" ],
-    ext_modules = [ Extension('llhttp',
+    packages = [ "llhttp" ],
+    headers = [ "lib/llhttp.h" ],
+    ext_modules = [ Extension('__llhttp',
         sources = """
             pyllhttp.c
-            llhttp/llhttp.c
-            llhttp/http.c
-            llhttp/api.c
+            lib/llhttp.c
+            lib/http.c
+            lib/api.c
         """.split(),
         language = "c",
     ) ],