Create csv plot download

[okanji]

The UI for a download csv button has been created. Now the functionality to get the data that the plot is showing needs to be built into a function. The current code downloads a mock csv file.

1. The UI for the download csv button is here:
   

   cmip6-BC/app.R

   Lines 143 to 144 in 275efda

   	# ~~~ Download csv data button
   	# downloadButton(outputId = "downloadData", label = "Download data"),

2. The body of this function needs to be edited to return the actual plot data as a data frame. Currently it returns a mock data frame:
   

   cmip6-BC/app.R

   Lines 333 to 339 in 275efda

   	# ~~~ Function to return plot data, using mock data currently
   	# getPlotData <- function() {
   	#
   	# # TODO: Need to return actual plot data
   	# return(data.frame(A=1:10, B=2:11)) # Mock Data
   	# }

3. The download handler that calls the function above and converts the data frame to a downloadable csv is here:
   

   cmip6-BC/app.R

   Lines 629 to 637 in 275efda

   	# ~~~ Download csv data handler
   	# output$downloadData <- downloadHandler(
   	# filename = "Data.csv",
   	#
   	# content = function(file) {
   	# write.csv(getPlotData(), file)
   	# }
   	# )

All of the above needs to be uncommented. Only 3. needs to be edited.