Separated the pure beliefstate system capabilities from the ROS related parts

The parts of the core beliefstate system that are ROS independent are now handled within the ''Beliefstate'' class. All ROS related enhancements (like handling the ROS workspace, and finding ROS package relative paths) are covered by the subclass ''BeliefstateROS''.

This is independent from the ''bs_plugin_ros'', which handles ROS related initialization, communication, and shutdown.
Moved evaluation of designator annotation-to-purpose-tag into separate function
Moved a great deal of information from the ''CExporterOwl'' class into the semantics descriptor file