Add option 'save WaterML files' to search download settings

jirikadlec2[CodePlex]
It seems that HydroDesktop is saving all the GetValues WaterML files to the C:\users\user name\appdata\local\temp\HydroDesktop folder. This uses large hard drive space on the user's computer. For example I found that the folder size with the WaterML files
was 2 Gigabytes after I downloaded all data from the 'Little Bear River experimental watershed' web service.

Improvement suggestion:

Add a 'save WaterML files' checkbox to the search download settings. If the checkbox is unchecked then don't save the downloaded WaterML files to the temporary folder.
Show the name of the folder where the WaterML files are saved (usually it's C:\users\user name\appdata\local\temp\HydroDesktop)

Start by locating the search download settings and the code that saves downloaded WaterML files in the temporary HydroDesktop folder. Add the requested save option and display the folder path; done means unchecked downloads no longer save WaterML files there while checked downloads continue to do so.

Written by the indexing model from the issue text.