Fix items from Volker Englisch's review of the preferences dialog.

[David Hampton]

Log Message:
-----------
Fix items from Volker Englisch's review of the preferences dialog.

Tags:
----
gnucash-gnome2-dev

Modified Files:
--------------
    gnucash:
        ChangeLog
    gnucash/src/business/business-gnome/glade:
        businessprefs.glade
    gnucash/src/gnome/glade:
        sched-xact.glade
    gnucash/src/gnome-utils:
        dialog-preferences.c
        preferences.glade
    gnucash/src/import-export:
        generic-import.glade
    gnucash/src/import-export/hbci/glade:
        hbciprefs.glade