Luigi Tibaldo / ctools

A specific parameter reloading is needed in case that command line parameters are provided.

This makes sure that the code also work in absence of the parameter file or a sysfiles folder.

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

The energy dispersion was so far neglected in ctmodel::get_obs.

# Conflicts:
#	ChangeLog

A FFT-based computation was implemented in ctskymap for the RING background, which is faster but less accurate than the direct computation.

… Also implement OpenMP support for multiple observations.

The cstsdist parameter interface is now much simpler, requiring on input either an unbinned, binned or stacked observation. If an observation definition XML file is provided it is assumed that the file only contains event lists.

…TE-END, TIME-OBS and TIME-END

# Conflicts:
#	doc/source/users/tutorials/beyond/index.rst