Add function to add markers at regular interval to plot

[davidclemens]

Use the MarkerIndices property of a line plot to add markers at specific intervals (as opposed to at every data point). The interval is expressed in units of the x-axis. See this idea snippet:

markerInterval = 2; % hours
[~,markerIndices] = unique(floor((xData - xData(1))/markerInterval),'stable');