python: initial impl of bindings using cFFI

A PoC that exposes single function
`enry.language_by_extension()` and a small
number of helpers to deal with string
coversion between Go<->C<->Python.

Signed-off-by: Alexander Bezzubov <bzz@apache.org>

python/enry.py

@@ -0,0 +1,40 @@
+"""
+Python library calling enry Go implementation trough cFFI (API, out-of-line) and Cgo.
+"""
+
+from _c_enry import ffi, lib
+
+
+def go_str_to_py(go_str):
+    str_len = go_str.n
+    if str_len > 0:
+        return ffi.unpack(go_str.p, go_str.n).decode()
+    return ""
+
+
+def py_str_to_go(py_str):
+    str_bytes = py_str.encode()
+    c_str = ffi.new("char[]", str_bytes)
+    go_str = ffi.new("_GoString_ *", [c_str, len(str_bytes)])
+    return go_str[0]
+
+
+def language_by_extension(filename: str) -> str:
+    fName = py_str_to_go(filename)
+    guess = lib.GetLanguageByExtension(fName)
+    lang = go_str_to_py(guess.r0)
+    return lang
+
+
+## Test
+
+
+def main():
+    files = ["Parse.hs", "some.cpp", "and.go", "type.h"]
+    for filename in files:
+        lang = language_by_extension(filename)
+        print("file: {:10s} language: '{}'".format(filename, lang))
+
+
+if __name__ == "__main__":
+    main()