(#18) Published the versionNumber function

Published the `versionNumber` function as `lz4.version()` and added a
test case for checking if it's working.

src/papi/lz4/init.cpp

@@ -3,6 +3,6 @@
 #include "module.h"
 
 static test_initializer modules([](py::module &m) {
-    auto lz4 = m.def_submodule("lz4");
-
+    m.def_submodule("lz4")
+        .def("version", lz4::api::versionNumber);
 });

src/papi/lz4/module.h

@@ -1,8 +1,9 @@
 #ifndef __CINT_LZ4_MODULE__
 #define __CINT_LZ4_MODULE__
-
 #pragma once
-
+
+#include "api.h"    
+
 namespace lz4 {
 
     class context {

tests/papi/test_lz4.py

@@ -0,0 +1,10 @@
+import pytest
+
+@pytest.fixture
+def lz4():
+    from cint import lz4
+    return lz4
+
+
+def testVersion(lz4):
+    assert lz4.version() == 10702