Easier to use input for the factor of safety allowable stresses

[AstroJohnPE]

The UI where the factor of safety allowable stress is enetered ("Results Contours > Stress > Safety Factor > Set Allowable Stress Values") needs to be more user-friendly when working with many parts. Instead of restricting the user to change the allowable stress one part at a time, there needs to be a mechanism to change multiple parts at a time. Perhaps:

1. A "Fill Down" command (Ctrl+D) like in Excel where the value is the top cell is copied to all selected cells.
2. Support multiple row selection using the Shift key or Ctrl key. Whatever the user types in the "active" cell is populated to all of the selected cells.
3. A command to select all of the rows that use the same material as the currently selected row.