This little script has proven to be a vauable debugging aid, so it got
some love. All the new properties from #8184 can now be set, together
with the option to generate internal gears.
LGTM has identified a number of minor issues with the FCGear Part Design
scripts. This commit addresses each of them, and also corrects two minor
spelling errors in the dialog. None of the errors or their fixes are
expected to result in changes to the functionality of the script.
