[Geany] RFC: removed Tabs and Spaces 'Hard tab width' pref

[Nick Treleaven]

Hi,
I've removed the 'Hard tab width' GUI pref for the 'Tabs and Spaces'
indent type. (This does not affect the other indent types). This is
because IME it is always 8, and removing it makes the dialogs clearer.

In case anyone has changed that option, the setting is still read
from the configuration file(s). 

If there is a good reason to keep it configurable in the dialog, please
let me know.

Regards,
Nick