ctools

I renamed the stat parameter of ctlike into statistic. The parameter is now set to DEFAULT which means that the default optimization statistic that is in the observation container is used.

I added statistic parameters following the same logic to ctbutterfly, cterror, cttsmap, and ctulimit. I have not yet checked if the statistic parameter is actually correctly taken into account, but I added a unit test for the ctlikelihood::set_obs_statistic() method that handles the statistic setting.

I also changed csspec so that it derives now from cslikelihood. In that way it can benefit from the ctlikelihood::set_obs_statistic() method. The observation container is no longer stored in self._obs but in the ctlikelihood::m_obs data member.

I checked that running csspec with default or CSTAT and running the script with WSTAT actually leads to different results, and that the corresponding likelihood functions got called. For reference, here the difference in the fitted SED for some test data:

WSTAT
2017-10-21T21:15:22:  Bin 1 .....................: 1.373113e-10 +/- 3.812628e-12 [< 1.754375e-10] erg/cm2/s (TS = 1087.498)
2017-10-21T21:15:22:  Bin 2 .....................: 1.045101e-10 +/- 3.041434e-12 [< 1.349244e-10] erg/cm2/s (TS = 1057.596)
2017-10-21T21:15:22:  Bin 3 .....................: 1.077106e-10 +/- 3.147502e-12 [< 1.391855e-10] erg/cm2/s (TS = 1113.398)
2017-10-21T21:15:22:  Bin 4 .....................: 8.732562e-11 +/- 2.718267e-12 [< 1.145082e-10] erg/cm2/s (TS = 1038.574)
2017-10-21T21:15:22:  Bin 5 .....................: 6.957374e-11 +/- 2.422369e-12 [< 9.379738e-11] erg/cm2/s (TS = 870.357)
2017-10-21T21:15:22:  Bin 6 .....................: 5.656150e-11 +/- 2.233978e-12 [< 7.890123e-11] erg/cm2/s (TS = 692.162)
2017-10-21T21:15:22:  Bin 7 .....................: 4.858075e-11 +/- 2.090007e-12 [< 6.948078e-11] erg/cm2/s (TS = 597.593)
2017-10-21T21:15:22:  Bin 8 .....................: 4.659159e-11 +/- 2.116632e-12 [< 6.775789e-11] erg/cm2/s (TS = 534.525)
2017-10-21T21:15:22:  Bin 9 .....................: 3.321563e-11 +/- 1.877694e-12 [< 5.199255e-11] erg/cm2/s (TS = 350.602)
2017-10-21T21:15:22:  Bin 10 ....................: 3.395876e-11 +/- 2.121357e-12 [< 5.517231e-11] erg/cm2/s (TS = 346.723)
2017-10-21T21:15:22:  Bin 11 ....................: 1.773108e-11 +/- 1.619726e-12 [< 3.392832e-11] erg/cm2/s (TS = 128.381)
2017-10-21T21:15:22:  Bin 12 ....................: 1.850342e-11 +/- 1.864752e-12 [< 3.715092e-11] erg/cm2/s (TS = 106.198)
2017-10-21T21:15:22:  Bin 13 ....................: 2.100709e-11 +/- 3.408607e-12 [< 5.509315e-11] erg/cm2/s (TS = 117.038)
2017-10-21T21:15:22:  Bin 14 ....................: 1.815640e-11 +/- 3.209699e-12 [< 5.025339e-11] erg/cm2/s (TS = 69.478)
2017-10-21T21:15:22:  Bin 15 ....................: 1.258479e-11 +/- 3.364222e-12 [< 4.622700e-11] erg/cm2/s
2017-10-21T21:15:22:  Bin 16 ....................: 1.066218e-11 +/- 4.353846e-12 [< 5.420063e-11] erg/cm2/s
2017-10-21T21:15:22:  Bin 17 ....................: 9.033290e-12 +/- 3.011809e-12 [< 3.915137e-11] erg/cm2/s
2017-10-21T21:15:22:  Bin 18 ....................: 7.653251e-12 +/- 3.827531e-12 [< 4.592856e-11] erg/cm2/s
2017-10-21T21:15:22:  Bin 19 ....................: 6.484044e-12 +/- 0.000000e+00 [< 7.132448e-11] erg/cm2/s
2017-10-21T21:15:22:  Bin 20 ....................: 5.493460e-12 +/- 0.000000e+00 [< 6.042805e-11] erg/cm2/s

CSTAT
2017-10-21T20:45:41:  Bin 1 .....................: 1.373656e-10 +/- 6.030624e-12 [< 1.976718e-10] erg/cm2/s (TS = 1088.775)
2017-10-21T20:45:41:  Bin 2 .....................: 1.042587e-10 +/- 4.794084e-12 [< 1.521995e-10] erg/cm2/s (TS = 1062.849)
2017-10-21T20:45:41:  Bin 3 .....................: 1.078725e-10 +/- 4.977025e-12 [< 1.576427e-10] erg/cm2/s (TS = 1112.421)
2017-10-21T20:45:41:  Bin 4 .....................: 8.762697e-11 +/- 4.295399e-12 [< 1.305809e-10] erg/cm2/s (TS = 1035.871)
2017-10-21T20:45:41:  Bin 5 .....................: 6.986765e-11 +/- 3.827805e-12 [< 1.081457e-10] erg/cm2/s (TS = 868.705)
2017-10-21T20:45:41:  Bin 6 .....................: 5.670564e-11 +/- 3.522832e-12 [< 9.193392e-11] erg/cm2/s (TS = 690.559)
2017-10-21T20:45:41:  Bin 7 .....................: 4.872281e-11 +/- 3.295550e-12 [< 8.167827e-11] erg/cm2/s (TS = 595.845)
2017-10-21T20:45:41:  Bin 8 .....................: 4.678697e-11 +/- 3.335691e-12 [< 8.014386e-11] erg/cm2/s (TS = 536.790)
2017-10-21T20:45:41:  Bin 9 .....................: 3.296117e-11 +/- 2.933138e-12 [< 6.229252e-11] erg/cm2/s (TS = 350.816)
2017-10-21T20:45:41:  Bin 10 ....................: 3.414304e-11 +/- 3.132408e-12 [< 6.546711e-11] erg/cm2/s (TS = 345.622)
2017-10-21T20:45:41:  Bin 11 ....................: 1.757857e-11 +/- 2.494777e-12 [< 4.252633e-11] erg/cm2/s (TS = 129.887)
2017-10-21T20:45:41:  Bin 12 ....................: 1.832112e-11 +/- 2.858257e-12 [< 4.690368e-11] erg/cm2/s (TS = 106.383)
2017-10-21T20:45:41:  Bin 13 ....................: 2.100710e-11 +/- 3.300950e-11 [< 8.577811e-11] erg/cm2/s (TS = 123.839)
2017-10-21T20:45:41:  Bin 14 ....................: 1.821459e-11 +/- 6.688968e-12 [< 7.087034e-11] erg/cm2/s (TS = 71.630)
2017-10-21T20:45:41:  Bin 15 ....................: 1.425697e-11 +/- 1.835423e-11 [< 6.219684e-11] erg/cm2/s (TS = 49.067)
2017-10-21T20:45:41:  Bin 16 ....................: 1.085186e-11 +/- 2.643605e-11 [< 1.362755e-10] erg/cm2/s (TS = 144.719)
2017-10-21T20:45:41:  Bin 17 ....................: 1.745800e-11 +/- 1.241720e-10 [< 3.450824e-10] erg/cm2/s (TS = 280.243)
2017-10-21T20:45:41:  Bin 18 ....................: 1.122167e-11 +/- 4.623641e-11 [< 2.467699e-10] erg/cm2/s (TS = 139.358)
2017-10-21T20:45:41:  Bin 19 ....................: 6.484044e-12 +/- 0.000000e+00 [< 7.279449e-12] erg/cm2/s
2017-10-21T20:45:41:  Bin 20 ....................: 5.493460e-12 +/- 0.000000e+00 [< 1.092135e-11] erg/cm2/s

I merged the code into devel.

I still need to modify all other cscripts that do maximum likelihood fitting (e.g. cslightcrv, csphasecrv).