add ability to request averages instead of instantaneous data for trends on displays

When looking at longer time intervals, pulling all data on a display of trends can lead to slow response. Often hour or day averages are more appropriate and would reduce amount of data that needs to be sent from PI server to user. If looking at 1 day of data, min snapshots are often appropriate. If looking at 1 month of data, hourly average or daily average might be more appropriate. When looking at multiple years for run length of a unit, daily averages work much better. Compression settings can help response/data amount, but often are inconsistently set. Using datalink and spreadsheet is another option but that is a second tool and PI Vision is better visualizing. Ability to override the default all data with average data like 1min/ 1hour/ 1day would help all users.