Add ability to view startup data from other menus

[dEhiN]

Taken from issue #43:

Add the ability to view a startup item or the full startup data from other menus

For the first point, currently in the menu to edit a startup item, there's an option to view the startup item. However, in the sub-menu from there to edit/add item arguments, there's no option to view the startup item. If someone edits, adds, or deletes an argument, they must return to the previous menu first in order to view their changes.

In the same vein, the menu to edit the existing startup file has no option to view the startup data. If any changes are made, particularly by choosing to add a new startup item or delete an existing startup item, it's necessary to first save the changes, then go back up one level, then choose to view the startup data.

Since currently the tool is CLI-only, it's already frustrating to not have a GUI to work with. Therefore, the options to view changes should be easily accessible. If possible, the changes should be viewable by themselves as well as within the greater context, without forcing the user to save the changes first.

[dEhiN]

Adding this to Back-Burner status because it may not be relevant anymore. If the Python CLI tool isn't going to be worked on or developed more, and if a graphical tool is going to be created as a replacement, then this issue may not matter.