Finalizing the merging

See merge request !3

Julien's most updated code has all valence derivatives with the sign changed, so md_val needs to flip the sign. Also, the reader does not write "_d1, _d2" in the derivatives anymore for the new data files, so md_val does not look for "_d1, _d2". You need to select by hand which correlators are your valence derivatives, looking at the log file e.g.

Updated dec_const to use plot_data and plot_func, added optional return for fig and ax objects, updated documentation

Updated meff to use plot_data and plot_func. Now the function output also fig,ax if pl is true. Updated documentation

Updated mpcac function using plot_data and plot_func, added overload for Vector{Corr}, added optional return to plot obj, updated documentation

corr_obs_TMS updated with gaps in measurements and automatic detection of the gaps

t0_phys changed from Bruno et al to the value from internal analysis

corr_obs_TSM now supports different statistics between sloppy and correction without neglecting the correlation. Extra flags idm_corr, idm_sl, nms have been added to allow this feature.
Documentation added