Allow for display of average stock map

All I did was add the option of displaying a new stock called "Average."

@gelo592: I changed the name so it would match with the display name and because to read which stock right now we convert the string to all lowercase. These would be easy to work around, but I figured it would be best to just change the name.

Also, my update to qt5 seems to be broken, so if one of you could test it to make sure this will actually display it that would be great.