bug#12749: num3-mode.el provides wrong feature

[Jonas Bernoulli]

The library num3-mode.el which has been added to the GNU Elpa repository
does not provide the correct feature, it provides `num3' which doesn't
match the filename.

Please eigher rename the library or provide the feature matching the
current filename.

By the way, this is the first line of the library:

    ;;; num3-mode.el --- ...

and this the last:

    ;;; num3.el ends here


Thanks,
Jonas