Leonardo Di Venere / ctools

Remove ctools::time_reference constant and handle the time reference for MET either by using the time reference from the input observation, or by adding a hidden "mjdref" parameter. The following tools transparently use the time reference of the input observation:
* ctselect (apply time reference of each input observation)
* ctbin (apply time reference of first input observation)
* csobsselect (apply time reference of each input observation)

A "mjdref" parameter was added the following tools:
* ctobssim
* cslightcrv
* cspull
* csviscube
* csobsdef

# Conflicts:
#	src/Makefile.am

The void constructors from ctools base classes are never used, tools are always constructed with a name and version number.

The ctool::get_roi() replaces some duplicated code in ctselect and ctcubemask. The method extracts the RoI from the user parameters "ra", "dec" and "rad". In case the "usepnt" parameter is present and set to "yes", the "ra" and "dec" parameters will not be read, and it's up to the client to set the RoI centre properly.

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".

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 constructs have been replaced by the new logger methods.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

The new GApplication logger support function take the chattiness level as the first argument.

# Conflicts:
#	cscripts/csiactcopy.py
#	cscripts/csiactdata.py

…lementing missing information from user parameters.

…oid code duplication in cscripts.