Fix RIDE when removing only import from SettingsTable.
Fix RIDE when removing only import from SettingsTable.

directory and source were None when SettingsTable __nonzero__ was False.
This happens when SettingsTable is empty and has no predefined header.

userzimmermann/robotframework-python3,userzimmermann/robotframework-python3,userzimmermann/robotframework-python3,userzimmermann/robotframework-python3,userzimmermann/robotframework-python3