- New `ctrl_wheel_font_zoom` runtime setting, on by default, persisted and
covered by the reset keys.
- Terminal appearance gains a switch for it, plus a search keyword.
- With the setting off, the Ctrl+wheel gesture is ignored as a whole: the
font size does not change and the terminal does not scroll.
- Plain wheel scrolling and the Ctrl+= / Ctrl+- / Ctrl+0 shortcuts are
unaffected.