Fitting

The scripts in experimental were used for debugging the fit.

Changes in the actual fitting used in the analysis:

- LL divided by number of templates
- gMinuit.SetErrorDef( 0.5 ) for LL errors (was 1)
- Remove constraints on QCD and V+Jets
- Set initial QCD template normalisation to 0.1 if less than 0.1


This is equivalent to setting
```
fit_var="absolute_eta,M3,angle_bl" 
```
and using it. Please remove the for-loop over one element

However, fit tests should use all combinations (as old code). This includes the single-fits that you use here.