As promised in #482:

Breaking change:
double comma ,, is now always required to start a description.
Single comma does not work any longer for this purpose.
If a single comma happens to be used by mistake,
the comma and the following text would end in the category.
So comma will be forbidden in the category,
to raise an error instead of merging a wrong fact in the database.
That will be the purpose of a forthcoming PR.

The same Fact.check is used from the command line and from the gui.