This directory contains wrapping layers on top of libraries which are
*external* to Batteries Included, but integrated into it nevertheless.

Each wrapper comes into its own directory, with the exception of the
following directories:

- common: contains modules and interface code shared by more than one
  	  external library, e.g., module types to be implemented by
  	  several external libraries

To each external library integrated into Batteries Included must
correspond a build- and run-time dependency of Batteries Included and
a dependency into Batteries' META file.
