This makes modifications in FontEditor more visible, both so you know
what you've changed, and for taking a handy "here's what's changed"
screenshot for a font PR. :^)
The background color for new glyphs is green, modified glyphs is blue,
and deleted glyphs is red. The changes persist until you load a new
font file, so you can continue saving your work as you go and still be
able to take a convenient screenshot at the end.
I didn't feel like this one use was enough to add 3 new color roles to
themes, so to make this look decent on dark themes, it detects if the
theme is marked as dark, and uses darker colors for the highlights
which look nice with a light text color.
GlyphMapWidget now reports context menu requests when secondary
clicking the map. This also adds a new Select All action and updates
the Copy Character action to work on multi-glyph selections. Glyph
navigation actions have been moved to a separate Go menu, as is
common in other apps.
Previously, if it was displaying N glyphs per line, then you changed
font to one that was a drastically different size, it would continue to
display N glyphs per line until you resized the window. Now, we
immediately recalculate how many to show, so that they fill the
available width. :^)
