Michael Mayer / ctools

# Conflicts:
#	test/test_csiactobs.py

The outcome of the unit tests depends on the presence of the CTOOLS environment variable. If the CTOOLS environment variable is not present the unit test should fail, otherwise it sould succeed.

The ctobservation::first_unbinned_observation() and ctobservation::next_unbinned_observation() methods implement an unbinned CTA observation iterator. Using this iterator avoids code duplication and generates a uniform interface for tools to loop over CTA events lists.

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

The pars() methods allow to assign or to retrieve all application parameters in a dictionary. Makes ctools a bit more "Pythonic".

This led to an invalid pointer problem before, is now fixed due to GammaLib fix.

Since the new GApplication logger methods are more compact than the old format the "logTerse()" etc. constructs have been replaced by the new logger methods. At the same time, the chattiness levels have been reviewed with the following behaviour:
- TERSE: only headers
- NORMAL: standard output, only main results or computations
- EXPLICIT: detailed output
- VERBOSE: verbose output, mainly for diagnostics

… cases, restructured csiactobs to avoid code duplication and added csobsdef::obs() function to retrieve observation container