Because no known icon theme (except the Breeze one) contains all needed icons,
we will now force Breeze theme for Krusader, if available. Otherwise we will
show a warning dialog.
FIXED: [ 372964 ] At least one Oxygen icon in Krusader is not correctly seen (using Kubuntu 16.04)
BUG: 372964
FIXED: [ 388691 ] Problems with "edit-select-none" icon and "edit-select" icon?
BUG: 388691