Allow to choose between the old and the new icon set

[pasoorii]

IMO it would be best to provide users with the option to use the old icon set, unless there is reason why this approach is entirely unrealistic.

[eumagga0x2a]

The reason it is unrealistic is that an additional button, not present in the old interface, was added together with the new icon set. Even if it were realistic, it is entirely WONTFIX.