Add single thread option to search download settings

twhitvine[CodePlex]
In Search tab, Download Settings button, you can tell HD to limit each each GetValues download request to approximately n number of values. The intent behind this option is to allow data retrieval from servers with limits on request volumes.

In testing, some servers still fail. It appears to be because HD download is still multi-threaded even when number of values per request is set.

I suggesting adding a checkbox to the Download Options dialog to allow the user to choose from multi-threaded vs. single threaded download. Multi-threaded should be the default, as it is now.

Start in the Search tab's Download Settings dialog and trace the GetValues download request handling. Add a single-threaded choice while preserving multi-threaded downloading as the default, then verify that the selected mode is used when limiting values per request.

Written by the indexing model from the issue text.