Common metapackage for all Robot OS client libraries

 This package is part of Robot OS (ROS). It is mainly used to find
 client libraries (via 'rospack depends-on1 roslang'). The roslang
 package is only of interest to those implementing a ROS client
 library. Client libraries mark themselves as such by depending on
 the roslang package, which allows rosbuild and other tools to perform
 appropriate actions, such as msg- and srv-based code generation. The
 roslang package itself contains no actual code.