Louis helper/Python 3.8: call os.add_dll_directory when importing lib…

…luis DLL.

Python 3.8 adds os.add_dll_directory to securely load DLL's from known locations, which affects Louis helper when trying to load liblouis.dll from NVDA executable folder. Therefore add NVDA executable path to known DLL directories through os.add_dll_directory, which resolves ModuleNotFoundError.

source/louisHelper.py

@@ -6,7 +6,11 @@
 
 """Helper module to ease communication to and from liblouis."""
 
-import louis
+# Python 3.8 changes the way DLL's are loaded due to security.
+# Thus manually add NVDA executable path to DLL lookup path for loading liblouis.dll.
+import os
+with os.add_dll_directory(os.path.dirname(__file__)):
+	import louis
 from logHandler import log
 import config