Josh Cardenzana / ctools

Changed the on time for a given bin to be set from the observation being filled into the cube rather than the cube itself.

Updated writing information to log file in order to prevent messy log file messages. This doesnt appear to impact the computation time.

Optimized computation intensive parts of ctmodel to reduce computation time.
Implemented openmp parallelization of ctmodel to reduce computation time.

So far any exception occuring during the construction of the ctools were not catched. This is corrected now.

All likelihood ctools now derive from the ctlikelihood base class. This avoids code duplication and provides all likelihood tools with a uniform interface.

The GCTAEventCube::map() method has been renamed to GCTAEventCube::counts() (#1789)

The publish parameter has been added to the following tools:
- ctbin
- ctbkgcube
- ctcubemask
- ctexpcube
- ctmodel
- ctskymap
- cttsmap

Although the get_obs() method was put back, ctmodel used the dummy cube (which consisted of a single pixel) instead of a cube defined from the input parameters. This was due to an internal change of the logic, that now has been corrected for.

Without the energy margin, roundoff errors may lead to the exclusion of the energy bin in case that a single energy bin is used.