Johan Bregeon / ctools

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

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 constructs have been replaced by the new logger methods.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

…lementing missing information from user parameters.

…ag in the execute() method.

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.

Added ctool::require_inobs_nocube() method that throws an exception if a counts cube has been specified as inobs parameter. This method is then used by ctbin, ctexpcube, ctpsfcube and ctbkgcube.

Conflicts:
	ChangeLog
	NEWS
	src/ctbkgcube/ctbkgcube.cpp
	test/test_ctools.sh

…in case that those are not provided in the event list.