[histogram] when an indexPattern is not timebased, set min and max properly
[histogram] let vislib handle min and max
[vislib] calculate min/max of an ordered date range
refactoring inject_zeros because the previous code was a mess
refactoring according to pr comments
Merge pull request #1710 from stormpython/feature/refactor_inject_zeros

Refactored inject_zeros component in Vislib
Merge pull request #1686 from spenceralger/time_based_histogram_bounds

Set min/max properly in histogram converter