Sylvie Brau-Nogué / gammalib

The saveto() method now also checks whether a file with the .gz suffix exists.

The former trigonometric method led to different results on different platforms due to numerical imprecisions. We now use Huilier's theorem to be less sensitive to numerical problems. The polygon is decomposed in two triangles for this purpose.

Conflicts:
	ChangeLog

Conflicts:
	src/sky/GWcs.cpp

When a pixel touches the pole, the pixel is effectively a triangle and not a polygon. This case is now handled properly.

The mc() method went in endless loops as the exit condition of the while loop was inversed (the method continued looping when the energy was within the valid range and only exited when it was outside).

The eval_gradients() method computed the gradients with respect to the parameter values and not the parameter factors. All gradients have be multiplied by the scales. Also, the gradients are now set to 0 if the parameters are fixed.

Finally, the parameter "Prefactor" was renamed to "Normalization" because the parameter gives the integral flux under the Gaussian, not the prefactor.

…ralGauss mc method as suggested