Removes unused imports as reported by LGTM.
There are exceptions: `import Arch_rc` is shown as an alert, but has side effects. It's not clear what the best thing to do in those cases is, so I've left them for now.
These functions were moved from DraftTools and DraftGui
to individual modules precisely to make them easy to import.
Otherwise we have to import the entire DraftTools and DraftGui
modules which creates dependency problems when we want to use
some functions without the graphical interface.