set xlim based on range for 1D histogram in the diagonal

[changhoonhahn]

I noticed xlim was not set for the diagonal 1D histogram so I added

ax.set_xlim(np.sort(range[i]))

to core.py

[dfm]

Thanks for this, but the xlims are already set a little lower (look for the call to _set_xlim) so can you share a demo that doesn't work with the existing logic first?