This includes `gui_utils`, `init_draft_statusbar`, `init_tools`,
`messages`, `todo`, `translate`, `utils`.
These are added to the `draftutils` Doxygen group
so that the functions contained in each module are listed
appropriately in the automatically generated documentation.
The functions `getDefaultUnit`, `makeFormatSpec`, `displayExternal`
are used to get the default unit schema for lengths and angles,
and display a string with a particular format.
They aren't used in `DraftGui.py`, but are used by the
viewprovider of the Dimension objects. Therefore, they are moved
into a separate module, so that they can be imported without
using the entire `DraftGui` module.
