Review LAT response classes.

GLATAeff
  read() method now take a const reference instead of a pointer.
  The clobber argument for the save() method is now a const
  reference.

GLATEdisp
GLATPsf
GLATLtCube
  The clobber argument for the save() method is now a const
  reference.

GLATPsfBase
  read() and read_scale() now take const reference instead of
  pointers as arguments. costhetamin(), front(), scale_par1(),
  scale_par2() and scale_index() now return const references.

GLATPsfV1
GLATPsfV3
  read() now takes a const reference instead of a pointer as
  argument.

GLATLtCubeMap
  read() and write() methods now take a const reference instead of a
  pointer. ncostheta(), nphi() and costhetamin() now return const
  references.

GLATMeanPsf
  offset(), energy(), dir(), name() and thetamax() now return const
  references.

GLATResponse
  caldb(), rspname() and force_mean() now return const references.

GLATResponseTable
  read() and write() methods now take a const reference instead of a
  pointer. nenergies() and ncostheta() return const references.
Update class documentation.
Adapt to new interface of response classes.
Remove GLATPointing class.

The GLATPointing class was not used, but implement because the former interface was requiring a class derived from GPointing. As GPointing has now been removed we can also remove the GLATPointing class.
Review Fermi/LAT observation class interface.

GLATObservation
  ltcube() method now returns a const pointer and response() method
  takes a const reference as caldb argument.
Update GLATInstDir class documentation.
Finish LAT module code review.

GLATEventBin
  cube() now returns a const pointer.

GLATEventCube
  enodes() method is now declared const.
Remove GCOMPointing class.

The GCOMPointing class is now obsolete as no GPointing class is required anymore. The pointing can now simply be stored in a GSkyDir object.
Finished COMPTEL module review.
Remove GMWLPointing header file.

Is now obsolete.
GEventCube::set_energies and GEventCube::set_times are now implemented as virtual dummy methods.

Implementing both methods as virtual dummy methods avoid the need for reimplementing dummy methods in derives classes in case that the methods are not needed.
Finish Multi-Wavelength module code review.

GMWLDatum
  energy_err(), flux(), and flux_err() methods now return const
  references.

GMWLObservation
  filename(), extno() and extname() methods now return const
  references.

GMWLSpectrum
  telescope() and instrument() methods now return const references.
Declare all methods implemented in the header as inline methods.
Declare access operators as const to assure const correctness of code.
Remove pointing test and GCOMPointing from COMPTEL header files.