Dynamic number of left hand columns

This addresses problems identified in issue #338

Updated to dynamically display one or two columns of configuration options on the left hand pane depending on the position of the splitter window slider and available real estate.  

The contents of the columns are smoothly sized under Windows 7 and Ubuntu/Gnome.  Under MacOS 10.8, the data entry fields do not resize which leads to white space because the columns are always the same size.  

Changing the behavior on the Mac is not critical but should be eventually fixed (if possible).

One feature that could be implemented (that would also work around the MacOS issue) is to have it that if you double-click on the splitter bar the display switches between 1 or two columns.  A potential problem with this is that what an ideal column width is subjective (user preference), language dependent and changes with the updates to the options panel.