enh(ui): update icons
Description
This is an icon overhault. Most "old" style icons have been replaced by "white" themed ones. This is a preliminary work, as the "flat" themed icons are still in use. The white icons pack may be updated again later.
Results
SightViewer should be left mostly unchanged.
How to test it?
- Launch Sight applications (SightViewer, ...)
- Launch applications that use the new icons