Add setting for the time format

[Mingun]

Is your feature request related to a problem? Please describe. I prefer to see exact times instead of relative ones. Currently the precise date of the commit can be viewed only in a tooltip in a details commit pane (bottom-right corner). It is impossible to see the exact time in the graph.

Describe the solution you'd like Add a setting with list of predefined formats or, maybe, a field with format string that will determine how to format dates. Add tooltips to the graph when mouse over date field:

Describe alternatives you've considered I think, there is no alternatives