Upgrading g-Octave

Quick notes for users upgrading from older versions of g-Octave.

From `0.3` to `0.4`

This version broke the compatibility with old package databases and some external files.

You'll need to remove the directories of the package database and the overlay (db and overlay options from the configuration file).

To know what are the current values, type:

$ g-octave --config db
$ g-octave --config overlay

And remove both directories!

If you installed g-Octave with USE="-sync", please remove those directories before run emerge --config g-octave.