Wrijupan Bhattacharyya / ctools

…s. This method is useful for debugging the memory usage of ctools.

…d scave() methods to ctool interface. Add read_ahead() method to handle reading of task parameters at the beginning of the task execution. Remove all m_read_ahead members from the derived classes.

…esponse for all CTA observation in the container that have not yet a response using the task parameters.

…ss for CTA observation response setting.

The ctool base class is now used in the ctbin tool. The get_ebounds() method has been moved to the ctool base class so that it can be used also in other tools. This reduces code duplication.