Add ability to handle pathlib paths

- Handle pathlib paths across all implementations, plat_other already did
- Move preprocessing code to common location

send2trash/util.py

@@ -0,0 +1,16 @@
+# encoding: utf-8
+# Copyright 2017 Virgil Dupras
+
+# This software is licensed under the "BSD" License as described in the "LICENSE" file,
+# which should be included with this package. The terms are also available at
+# http://www.hardcoded.net/licenses/bsd_license
+
+
+def preprocess_paths(paths):
+    if not isinstance(paths, list):
+        paths = [paths]
+    # Convert items such as pathlib paths to strings
+    paths = [
+        path.__fspath__() if hasattr(path, "__fspath__") else path for path in paths
+    ]
+    return paths