meldwindow: Add a second toolbar to pack a progress indicator in
Remove most old statusbar usage and progress display code

This removes the perms and time displays from folder comparisons, since
we have actual columns for those now. The progress display is removed
in favour of using a spinner in the toolbar.
Remove statusbar from everywhere except file comparison

This commit also removes the hooks for showing detailed messages on
menu item hover; while handy these aren't present anywhere in modern
GTK 3 apps.

Also, this makes the statusbar always appear in file comparison mode.
ui.statusbar, filediff.ui: Fix some statusbar styling and packing
filediff: Add a toolbar to each pane, adapting controls and styling

This commit also adds a save button to each pane for a more obvious way
of saving individual files that isn't based on current pane focus.
filediff: Reformat widget lists
linkmap: Clip drawing to textview extents and add bottom border
css: Fix spacing of toolbar
filediff: Fix and reformat per-pane widget hiding
dirdiff: Migrate to same in-pane toolbar as filediff
vcview.ui: Resave with new Glade
vcview.ui: Migrate to toolbar style
dirdiff/filediff: Set expand in UI file instead
vcview.ui: Fix some spacing and styling issues
vcview: Update the console-box UI to a View menu item and little else
vcview.ui: Make the console output somewhat more obvious