Add GObservations::logL() method and add const attribute to GOptimizerFunction::value() method.
Add rampdown to Psf access operator at the edge of the Psf so that no steps occur in the log-likelihood function.
Add offset subtraction to provide smooth Psf edges.
Add missing methods to Python interface
Use a sqrt delta binning and add a central cap.
No need anymore to add 10% margin to delta range.
Avoid unnecessary computations.
Correct indentation
The romb() method now returns a result even if it is inaccurate.

Before, 0 was returned in case of inaccurate results. This is bad. We want some result, even if it's not accurate.
Add smooth_robust() method to compute smooth noise-robust derivatives.
Some code changes in the course of the Irf integration investigation.
Add fixed_iter() method and implement fixed iteration handling in Romberg method.
Add left_difference() and right_difference() methods.
Add romberg() method variant that takes a vector of (unsorted) boundaries. The method will sort these boundaries and returns the sum of the integral over all boundaries. This allows easy splitting of an integration range into two pieces by adding an internal node.
Adapt model and Npred gradient computation to cope correctly with parameter boundaries. Also streamlined the interface to avoid passing parameter indices. We now pass parameter references.
Adapt CTA response integration helper classes to a fixed number of iterations.

Due to numerical stability it is adviced to use a fixed number of integration iterations instead of fixing the integration precision. The latter leads to substantial numerical noise that make computing of numerical derivates very difficult.
Modify response computation so that a fixed integration iteration depth is used instead of a given precision.
Remove integration precision eps().
Now runs full benchmark test over all model types and analysis variants.
Remove GCTAResponseIrf::eps() method.

This method is now obsolete as we do not use integration precisions anymore.