fgl directory layou

[Ross Paterson]

Sven Panne writes:
> I think it would be highly desirable for the recently added fgl
> package to have a directory structure similar to the other packages in
> fptools/libraries, [...]  Keeping things similar makes scripts, packaging,
> etc. much easier and we should spend our creativity probably elsewhere...
> ;-)

and the package config file could be renamed package.conf too.