Use unified implementation for ffi::datetime

In the future we can make ffi::object, ffi::pycapsule, etc as
crate-public, but importing the specific symbols is a light touch way to
do this.

Author: pganssle

src/ffi3/datetime.rs renamed to src/ffi/datetime.rs

@@ -1,6 +1,7 @@
-use ffi3::object::*;
-use ffi3::pycapsule::PyCapsule_Import;
-use ffi3::pyport::Py_hash_t;
+use ffi::{PyObject, PyTypeObject};
+use ffi::{Py_TYPE, PyObject_TypeCheck};
+use ffi::PyCapsule_Import;
+use ffi::Py_hash_t;
 use std::ffi::CString;
 use std::ops::Deref;
 use std::os::raw::{c_char, c_int, c_uchar};

src/ffi/mod.rs

@@ -0,0 +1,12 @@
+#![allow(non_camel_case_types, non_upper_case_globals, non_snake_case)]
+#![cfg_attr(feature="cargo-clippy", allow(inline_always))]
+
+#[cfg(not(Py_3))]
+pub use ffi2::*;
+
+#[cfg(Py_3)]
+pub use ffi3::*;
+
+pub use self::datetime::*;
+
+pub(crate) mod datetime;

src/ffi2/datetime.rs

@@ -16,7 +16,6 @@ pub use self::cobject::*;
 pub use self::code::*;
 pub use self::compile::*;
 pub use self::complexobject::*;
-pub use self::datetime::*;
 pub use self::descrobject::*;
 pub use self::dictobject::*;
 pub use self::enumobject::*;
@@ -67,7 +66,6 @@ mod cellobject;
 mod classobject;
 mod cobject;
 mod complexobject;
-mod datetime;
 mod descrobject;
 mod dictobject;
 mod enumobject;