Update the themes dir during execution, and not at module level

src/poezio.py

@@ -33,6 +33,9 @@ def main():
 
     from config import options
 
+    import theming
+    theming.update_themes_dir()
+
     import logger
     logger.create_logger()
 

src/theming.py

@@ -511,8 +511,6 @@ def reload_theme():
     else:
         return 'No theme present in the theme file'
 
-update_themes_dir()
-
 if __name__ == '__main__':
     # Display some nice text with nice colors
     s = curses.initscr()