allow the user to explicitly define the histogram windows

-------

- gauge-view: interval selection dropdown 

- histogram longtail cap

- async report generation / cache heatup

- report: print number of samples, interval-size on topright via scalaexp-buttonstyle

- caching

      end

    end

    if @opts[:value_ranges]

      @histogram_mode = @opts[:value_ranges]

    else

      @histogram_mode = [23, @histogram.max || 1].min

    end

    @mmm_timeseries_arr = @mmm_timeseries.to_a

      .map{ |k,v| [k, Hash[v.map{ |vk, vv| [vk, (vv.is_a?(Numeric) || vv.is_a?(Array)) ? vv : 0 ] }]] }

      .sort{ |a,b| a.first.to_i <=> b.first.to_i}

  end

  def histogram(windows)

    Hash[histogram_windows(windows).map{ |w| [w,0] }].tap do |histo|

    windows = histogram_windows(windows) unless windows.is_a?(Array)

    Hash[windows.map{ |w| [w,0] }].tap do |histo|

      self.each do |k,v|

        histo.detect do |win, wval|          

          histo[win] += v if win.include?(k)

    elem: $('.widget_histogram_bars'),

    height: 320,

    no_headbar: true,

    values: #{@histogram.json_histogram([23, @histogram.max || 1].min)}

    values: #{@histogram.json_histogram(@histogram_mode)}

  });