Obtain GNUnet's default configuration (patch)

[Alessio Vanni]

Hello,

as the subject of this mail says, the attached patch implements a
function to obtain the default configuration used by GNUnet.

The main purpose is a convenience for applications using
`GNUNET_OS_init' to change the project data.  After changing the project
data it's impossible to obtain GNUnet's configuration without manually
examining the filesystem and that can become a problem when the
application needs to connect to GNUnet's own services
(e.g. gnunet-service-cadet.)

With this new function applications can retrieve the configuration even
after calling `GNUNET_OS_init' (or at any other point in time, really.)

Please review it so I can fix anything if needed.

Thanks,
A.V.

0001-Add-function-to-return-GNUnet-s-default-configuratio.patch
Description: Patch for GNUnet