* Text editor word wrap, line numbers & syntax toggles now use consistent icons
that don’t change when you enable or disable them.
* Replaced icon toggle buttons in the snapping popover with normal checkboxes
and descriptive text labels. This makes it clearer which item is the main
radio button, is more consistent with other popovers, and allows us to use
more descriptive text.
* Added correct icons for grease pencil add menu.
* Added bespoke icons for grease pencil modifiers.
* Added icon for particle instance modifier.
* Added icon for fake user on & off states.
* Added correct icons for enabling/disabling modifiers in the dopesheet &
f-curve editor.
* Made it so the restrict viewport & restrict render toggles for modifier
update correctly when enabled or disabled, by flipping the order in the
icon sheet. This also required changing the outliner to match.
* Removed the few old remaining icons in the old style and made sure to replace
the last places where they were used.
* Updated many icons to be clearer & more consistent.
Not much to add, modifier uses same code as operator basically, only key difference
is that modifier will never create data layers itself, you have to use dedicated operator
for that.
