Alignment fixes, only use single row when labels not shown
Fixes #83 (closed) #64 (closed)
The two options "single row" and "show scrollbox" have now the following meaning:
- single_row=true, show_scrollbox=false: single row square button occupying a single row of the panel.
- single_row=false, show_scrollbox=false: full panel size button, no labels, length defined by the icon (perhaps this could be removed in the future, if non-square button is not needed, along with the single_row option)
- show_scrollbox=true: full panel size button with labels, length defined by the icon+labels.
- (single_row=true, show_scrollbox=true: removed, same as show_scrollbox=true. Looked ugly and had questionable usability)
Deskbar mode is now treated like other modes. Having a single-row icon button is more useful than a second icon+label layout that requires a lot of horizontal space.
General alignment of the icons/labels, mostly centering them in the plugin and boxes.