Color code operations

This topic requires experimentation, because it might turn out to be not so good, but I think it wouldn't hurt if each type of operation had its own class, so it is possible to attribute different operation name color and background color to each operation. It holds true even if we end up grouping many operations within the same color scheme. Default differences should most likely be very subtle, f.e. virtual operation names should be slightly yellow instead of white, and the background color for social operations should be a bit different than financial or account management operations.