- resize to 24x24px
- use KiCad icon colours (#545454)
- rotate to match top-left = off, bottom-right = on of other mode select icons
- adjust node sizes to match other ratsnest icons
- unify diagonal line with other icons
CHANGED: The margin used in 'Zoom to Fit' is now 2% instead of 10%.
ADDED: Added 'Zoom to Objects' to Eeschema which does not include
the page and border in the bbox calculations.
CHANGED: Removed pre-existing code that tweaked the center to account
for the scrollbars. It actually made the view off center. Removing it
results in perfectly centered zooms.
Fixes https://gitlab.com/kicad/code/kicad/issues/5145