Slight modifications

Updating tests ready for those that require additional values (e.g.,
alpha for quantiles and confidence intervals)
Allowing alpha values

Letting users enter an additional value (i.e., alpha) when selecting
tests that require an additional value.
Menu changes

Some changes to the menu with undo/redo functions for WebView.
Summary of navigation menu

Also wondering if the menu shouldn't be standard between grid & output
New preferences dialog

New dialog for users to enter preferences