Johan Bregeon / 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.

…ovided by the base class

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.

ctmodel now always produces a single model cube on output. There are two important input parameters: "infile" and "obsfile". "infile" specifies a counts or model cube that is used to define the binning of the model cube. The functionnality for this parameter is as before. If "infile=NONE", the cube will be defined according to task parameters that specify the spatial and the energy binning. The "obsfile" parameter is new and allows specifying the observation definition for which the model cube should be computed. If an event list or a counts cube is presented, the pointing and Good Time Intervals will be extracted from the FITS file header. If an observation definition XML file is presented, ctmodel will now loop over all CTA observations in the file and add the model values to the model cube. If no response information is associated to the "obsfile" (which is typically the case for event lists or counts cubes), the "caldb" and "irf" parameters will be used to identify the response.

- change evfile parameter to infile
- added irf and caldb parameters
- use pointer to GModel for test source
- clean exception handling
- minor code adjustments