Simon Bonnefoy / ctools

…cripts now from csobservation instead of cslikelihood since they do not use proper optimizers.

The scripts cslightcrv, csphasecrv, cspull, cssens, csspec, cstsdist, and cstsmapsplit now have a "statistics" parameter to allow setting of the optimizer statistic. Except of cstsmapsplit, all of the scripts now derive from the cslikelihood base class.

# Conflicts:
#	ChangeLog

# Conflicts:
#	ChangeLog
#	NEWS
#	doc/source/admin/release_history/1.5.rst

Removed 'runavgalpha' option, since computing the run-by-run significance is a non trivial thing and the difference in the residual counts map is negligible.
Added special handling in the significance computation when Non=0 to avoid NaN's.

Fixed a bug when doing the ring background subtraction where the significance being computed did not have the correct sign.

…tskymap_RING_bkgsubtract