added workaround for barplot annotations having NaN position
Created by: wilsonmr
closes #363 (closed). Before creating annotation, check if the coords are finite.
Also reformatted plot_fits_datasets_chi2
to look nicer if datasets match but experiments don't. Made the change at the level of dataplots.py
since changing fits_datasets_chi2_table
breaks some other tables and plots.
In the long term probably a better fix comes from #226 (closed)
example new plots: https://vp.nnpdf.science/dPqS5Q0qSIW-K1BBTgRY0g==